It’s going to have to be a 4 cylinder, unless I’m terrible lazy - in which case it will probably be a 6 (I.e. the 323i that is currently sitting in it).
It is as close to an M3 shell as you can get without it being original: new M3 bonnet, front quarters, doors, rear quarters, inner tubs, rear screen surround + interior trim, but 2nd-hand bootlid, front and rear bumpers. It is a 4-stud e30, originally a 323i manual but with some bits swapped out from a 1983 323iM (the orange 2-door that was brought over for the 1984 Auckland motor show).
The original body was vandalised, and having contacts made these parts close to the cost of standard parts at the time. Of course, many parts are no longer manufactured for these cars, so there could be some challenges along the way.