.. you can get 16v's with heated leather interior if thats what you want it for? thats what i have..
AFAIK they arent recaro's though, and arent electrically adjustable.
and (LOL) they are colour coded.. the car is black, so is the leather and the piping?

seems like a very long winded approach to getting heated/leccy adjustable leather seats to me..
if it is just about the seats i'd get a 16v either with or find aand fit a leather interior (they come up on ebay often) then later find some nice recaro's (maybe from a mk4) and have modded those to fit..
this will also make your life a lot lot simpler as far as insurance goes.. rather than claiming "a mk3 8v with a 16v engine".. you'll be claiming "a mk3 16v with cosmetic mods"
OR... save the engine transfer work and put the money into chipping an 8v.. people claim good results from doing that.. also.. most 8v owners seem happy with what they've got.. and some claim they're better than 16vs...