Engine Swap BMW 1992 735 3.5 into 1986 635

Anybody know if I will experience any problems transplanting a 1992 3.5 motor and auto trans into a 1986 635? I have been told the engine mounts may not align and I might have to fabricate new mounts or adapt the old ones. The 1992 trans is a 4hp-22. Will the mounts line up? How about electronics, any incompatabilities? Can I use the 1992 air flow control or would the stock 635 be easier? Any advice would be great! THANKS!