Replacing a gas stove
Go the stove manufacturers' websites and read the installation manuals for the stoves, checking particularly for installation clearances.

You could also replace the drywall behind the stove with 5/8 or 1/2" (depending what the surrounding drywall is) tile-backer (cement-board) and/or cover it with 1/4, 1/2 or 5/8" spaced off the wall surface by 1/2" to 1" (look up "woodstove wall-protectors" for the idea) and cover with aluminum foil if going for the last bit of effect. Aluminum sheet (flashing material) spaced off the wall has a similar effect (radiant barrier.)

You may well have damaged (or missing) insulation in the back of your current stove if it's heating the wall that strongly.