BMW M50/M52 engine? Or any other suggestions?

[Nickp]

Hi all,

I've just made an impulse buy of a new Haynes Roadster chassis with loads of other bits (suspension arms, shocks, hubs, steering, lsd, shafts race tank etc etc) off a mate for what seemed like a bargain price.
The 1st big decision I guess I need to make is what engine/box to use in it. I don't really want to use a 4-pot, unless it was a very light, powerful, revvy motor - which'll cost big money!! Not really fancying going the bike engined route either, not sure why?? The guy I bought it off was planning to put a BMW straight 6 2.8 M52 engine and box in there. It's an all alloy lump, so relatively light for its size but I have 2 questions-
1. Will it fit?
2. Is it going to upset the handling too much?
They're a good strong / powerful engine that'll give 230BHP with minor mods and can be picked up for peanuts. Just the job if it'll go in!!
If not, then what other suggestions do people have?
Must be-
Multi-cylinder (V8, V6, straight 5 / 6)
Light(ish)
RWD config
4 valve (no RV8 ta)
Cheap

Cheers,
Nick

Sorry for all the noob questions, but I'm sure there'll be plenty more