Several days ago, there was a thread about putting a current M62 V8 in an E9. I've done some rough measuring. It looks like the V8 is roughly 27" long, wide and tall. Width is the problem. If you were to take EVERYTHING out of the coupe engine compartment, it might fit. Biggest problem is going to be the brake booster/master cylinder. This is the case for E9 Motronic conversions too and the solution has been to adapt the E28 hydraulic boost setup. I'm not sure there would even be room for this with the V8. I just had a bare V8 long block to measure (car owner drove through some deep water, which was sucked up into the intake and into the engine, causing instant lockup, sending broken connecting rod through the bottom of the oil pan = $20K bill!) and haven't had a 6 speed to measure, but my expectation would be that that will be too big to fit into the E9 transmission tunnel. More fabrication .....