Good project. You can take a look at mine if you want:
Tarm Landed. I put both the 1000 gal tank and the Tarm in the shop.
You will want to size your lines between the boiler and the tank based on how many btu's you would the ability to move. The EWB200 is rated at 200,000 btuh, which likely is peak output. If you want to be able to move 200,000 btuh with a delta-T of 20F, then you need to move 20 gpm of water (btuh = gpm x 500 x delta-T). Work the formula anyway you want based on your objectives. 20 gpm normally would require 1-1/2" pipe. Then calculate pump head based on the length of your lines and pick a circulator that provides the required flow in about the middle of the pump curve.
Installing a 1000 gal tank vertical would be a challenge, both for engineering and for safety; mine is horizontal. I had 2" fittings welded into one end of my tank, 6" down from the top and 6" up from the bottom, supply to the top and return from the bottom. The top fitting has a 1-1/4" pipe extending horizontally 18" into the tank, and my supply and return lines are 1-1/4". Since this is a new setup from what I had last year, I don't have final data on stratification/mixing, but my first two test burns this summer (too hot to do any more) evidenced very good stratification, end to end, at a calculated flow of 14-16 gpm. My test measurement of stratification is based on sensors at each end of the tank, fixed to the outside and covered with insulation, one down 12" from the top and the other at the bottom of the tank. I now have 4 sensors installed on each end of the tank, top, down 12", down 24", and bottom (my tank has a 36" diameter). Come Sept and more data will be available with the first burns of the heating season. I'm pretty confident that stratification will be very good, but the data will tell the true story.