IIRC, the SHO V6s are really, really big too. If I'm not mistaken, a Small Block Ford with aluminum heads and intake is both lighter and smaller in every dimension (especially height) than a SHO V6. That could be something my brain made up though; I've been taking a lot of cough syrup recently.
My vote for compact, powerful, and cheap would be a 2.0 DOHC Neon motor and transaxle. They're dirt cheap, easy to find, and there's a significant aftermarket for them. They also make really good power for their displacement, even stock.
