Best high temp paint

Stove Bright.
That is also the original company that supplied Fisher originally. (Forrest)
Satin Black is closest to original if you have a black stove.

Here's a newsletter with some history of the first colors other than black requested by Fisher. They were just down the road from the first large, and Bob's own Fisher fabrication shop.
http://forrestpaint.com/wp-content/uploads/2013/07/FP-employee-newsletter-July-13.pdf

Color is personal preference. Any high temp paint is OK. Stove Bright holds the color longer without fading. It does smell the worst of any brand, and it's best to sand outside, paint and fire it for final cure outside. Stay away from Stove Black which is more suited for rough cast iron. It also allows water right through and will rust needing to be polished frequently. All iron; cast doors and steel plate was painted on Fisher Stoves.

To allow the stove to heat the upstairs, you need the heated air to rise near the stove, then cool upstairs and drop back down on the other side of basement to be drawn back towards the stove and rise again. (Codes now require a self closing fire damper in the opening between floors). Getting the heat to rise is no problem as long as you have return air. Returning the cooler air back down is much quicker with a fan in the duct (floor opening) allowing the heat to rise much faster, balancing the two levels.
The best balance is multiple vents over stove for rising hot air, and a stairway at opposite end of basement to allow the cooler air that has circulated across the building upstairs to drop down the stairs like a waterfall. The greater temp differential above the stove has no problem rising through the vents, but has less temp differential on the way down, so it needs a much larger area to slowly drop. Since yours sounds backwards, you can see how a small blower helping it back down at the coolest point upstairs will make circulation much better.

Do not use Stove Bright in a confined space. It is one of the last Acetone based paints and that stuff is nasty. Last time I painted a stove indoors with it I was woozy for a week. Never again.

This is what the metallic brown Stove Bright spray paint looks like.

We don't know what year your Grandma is, but the metallic brown wasn't made until after 1980 for the Grandma IV. (with glass)
Early Stove Bright color would have been Satin for Black or Bark Brown. (non-metallic)

Mybooman, here's Stove Bright Metallic Black;

This was not an original color offered and the nickel plated door was not available until 1980 when the doors had an arched top called "Cathedral". This is a custom stove with plated door and draft caps.

Another high def of metallic black. Again, the doors and draft caps were sent out for plating and not original. It gives you an idea of metallic black by Stove Bright.

This is a good example of the Metallic Brown. (Not Honey Glo)

Depending on light, it has a purple hue that is really sharp with brass.

Draft Caps show correct color in this light;

Aluminum cap in front, solid brass 4 in back. They are all original (new) caps that were never put on stoves from fabricator in Colorado. The black in rear is Satin.

Stove Black goes grey pretty quickly. It requires an annual reapplication and makes the stove hard to paint at a later date.

Not sure, probably a strong solvent, perhaps multiple times. Stove black is made from waxes and inks I think.

Primer? Is it also high heat by Stove Brite? Normally one does not prime a stove for repaint.

I have never primed a stove for repaint. You should wire brush the rust and use a drill powered wire brush for the tough stuff. Get rid of the surface rust, wipe down with a solvent like alcohol, then paint in a very well ventilated area.

Don; Lots of reasons not to use it on steel plate. #1 is that water and water vapor go through it and will rust through the coating. It is made to polish rough cast iron. It brings out the detail in intricate castings without filling crevasses, but is like smearing shoe polish on a smooth flat surface. Removing stove black is more difficult on cast iron which it is made for. Lacquer thinner works, it appears to take lots off. But if you fire it up, then wipe again, it's almost just as black on the rag ! I've torched the surface, wire wheeled then wiped with thinner, and it still comes up black after warming it up. Cast iron door is worse. Once done with polish, I just keep polish on the door.

Mark; The primer is only for exterior use like pipe, boilers and good for traction equipment. (steam rollers, traction engines, or outdoor stationary engines)
Don't paint over any rust. Wirewheel or sand to bare metal. If pitted, you can let some paint start to solidify in a small container and wipe it on with spackle knife or plastic scraper like filling with body putty or thick primer used in automotive body work. Lightly sand with 220, wipe with mineral spirits before final coat.
1 1/2 to 2 spray cans should give you two coats.
Nothing is done on the inside.
If you paint it outside, let it dry to the touch, you can fire within an hour. Then take inside when cured. You won't have to move it with uncured paint.

Here a Mapa Bear was wire wheeled and painted within a couple hours and fired in the same spot. I delivered it still warm in the back of a Land Rover and let me tell you a LOT of heat radiates off these when put in a truck with you warm ! I didn't have time to let it cool fully - it was a hot ride I'll tell ya.

The heat probably has baked off most of the oils and wax by now. Wire brush it down and then wipe it down with a good solvent like acetone (with protection). Then paint.