You need to consider the Euro 635 CSi motor
Acat, I've been in carb and fuel injected B35 equipped E9s and those are certainly nice and very common as you point out. My mechanic just completed my 1984 B34 Euro 10:0.1 compression ratio engine swap. We used L-Jetronic intake pieces from a late 70s 5 Series combined with the injection system and ECU from a 1989 635CSi and 735. I consider this motor the finest single overhead cam engine BMW ever built inside the M30 family. The short block only needed bearings, seals and an oil pump; the pistons, rings, etc were in great shape so only $500 was needed for all that. The head had some mileage on it and at least one loose valve guide, so we did a valve job, clean up and pressure test for less than $500; that is good piece of mind so I can drive this car 100-200K miles without worry of structural top end things going wrong. All other mechanical parts were junk yard pulls with some clean up, except for 02 sensor, spark plugs and gaskets, etc of course.
I've not dynoyed her yet but she pulls like a freight train and revs like a motor cycle engine. We are still tweaking the intake/fuel management pieces, but I'd estimate I'm getting at least the 218 crank hp and 225 lb ft of torque this engine was supposed to provide with its original ECU. Depending on how the next few weeks go, I might add a B35 exhaust manifold (I kept my stock exhaust for now and simply added an O2 sensor on one of the downpipes) with larger diameter pipes and resonator, and the Dinan chip.
Honestly, though, I'm amazed at the power increase already.
I also can't endorse my mechanic, Don Lawrence, enough. If you want his contact info or to discuss this more, send me a pm. Good luck.
I will post a long write up and pictures before too long.
Happy turkey day everyone!
Wayne