With enough cutting, chopping, welding you can put -ANY- engine and transmission in a PV. I've seen a few with large US V8 drivetrains squeezed in. I think it often involves replacing the front suspension and subframe, as well as cutting and chopping on the firewall and tunnel. My own personal opinion is the time, effort, and money is better spent on pepping up a B20 instead. You won't ever get the massive pull of a big block V8, but you can get a powerful car that still handles well. Pepping up a B20 is an often discussed topic around here.

If you are talking about just putting a BW35 with a B18/B20 in a PV then I'd be 95% certain the wider bulkier tranny won't fit without some modifications to the transmission tunnel - just as the OD manual tranny requires some work. The PV tunnel is -just- barely wide enough to clear the skinny M40 case - and immediately narrows down behind it. Doable if you aren't squeemish about cutting a huge hole in your car and doing a lot of welding to replace it.