100bhp/litre is a pretty good number!
You might be able to get close to 250bhp. The thing is that the first 30 - 40bhp is easy..... the more you want then the more difficult it gets.
Thought about doing a transplant?
The reliability will be questionable. To avoid problems with the engine you can change the gasket and leads for thicker, stronger ones which will help but we're talking a lot of cash for small reward here.
Drop the cash on a V8 engine from a 540i! That would be sweet.
<span style='color:blue'>"So my BM makes me a flash bastard? Then I guess you're just keeping it real from the seat of your nova?"</span>
<span style='color:gray'>"...and the home of the brave..... is bravey 130bhp from a 7 litre engine? 100bhp/litre or don't bother building it!"</span>
<span style='color:red'>"Aaahh the UK; where every road is jammed, under construction, poorly maintained and unfairly policed, at least we don't get over-taxed for it........ HA HA HA!"</span>