Need advice on older VC Defiant

So I've used this site for information many times and have finally found a Vermont Castings Defiant that's in good shape for a decent price. I'm picking the stove up this week but I have a concern that I could use some help with. I plan on putting this monster in the fireplace opening, and it's too tall with the feet, even so if I purchased the smaller feet. It will however, fit nicely if I remove the feet completely. Is this something I can do? I believe my fireplace opening is 28 1/2" tall. The stove is a rear exiting by the way. Any help or advice is greatly appreciated, thanks!

Correct, a traditional masonry fireplace. I can take a picture when I get home from work.

The opening seems plenty wide and I don't plan on stuffing this stove completely inside the fireplace so I should be able to reach the air shutter. There is no upper mantle on the fireplace, all brick and there is a 20" section of concrete hearth that extends out past the brick. I plan on having the stove about halfway exposed onto that hearth extension which is also about 12" off the concrete floor.

Yes I believe I could get an inch maybe 2 off but then the top of the stove would be very close to the top of the fireplace. If I remember correctly the measurement from the floor to the top of the fireplace entry was 28 1/2". I'm pretty sure the Defiant is 25 1/2" tall with no legs.

Here's what I'm working with. Also, is it possible that my chimney isn't actually 8"? It's hard to tell but it doesn't appear to be if so. The flue is only about 6" wide as well which is going to make getting an 8" flex through difficult. Would I be ok if I just ended the outlet elbow right under the flue flap and surround it with insulation? I appreciate the advice so far.