The s14 would be the engine to buy, IMHO, if you are contemplating that sort of thing. You know the saying..... go big, or go home ;)
Not cheap, though.
I found this tonight on another BMW forum, thought there may be some interest here.
"s14 conversion for sale
I have an s14 from an 88 E30 m3 for sale. Comes with engine, trans, wire harness, control unit, air flow meter, air box, alt, ps pump, a/c compressor. Engine ran great when i pulled it. I did a compression test before i purchased it and it was a dead even 210 across all cylinders. Oiled cylinders before storing in dehumidified garage. 122045 miles on the m3's clock. Engine was supposedly freshened up 15k ago. I have no proof of the "freshening up" but i do know it's a solid engine. Should be everything here for a 2002 transplant. $5000 firm for all. Can email pics. Please just email me at email@example.com for pics or any other questions. I find this site hard to communicate on. thanks."
Here is a little update, thanks to mlytle in 2002FAQ. If you are thinking of doing an "M2" conversion to your 2002, here is a link to a kit you can buy from Aardvarc Racing to help the process along: