If you wanna go fast and straight; then I guess one could stuff a V8 in one, but for better driveabilty, a V6 (aluminum block if possible) takes a LOT of weight off of the nose.)
I’ve always wondered about opening up the trunk area and putting a front wheel drive engine back there; relocating the gas tank to the front.
I suspect the flat-4 engine out of one of those new Subaru/Scion RWD cars would be perfect for the Opel GT. Low center of gravity, no problem with hood clearance and 200 hp without a turbo. Or, if you're more ambitious - the entire AWD drivetrain out of an Impreza. Upgrade to WRX specs later and really make the trees get all blurry.
Ive always wondered about opening up the trunk area and putting a front wheel drive engine back there; relocating the gas tank to the front.
I think it has already been done. At least "Mellow Yellow" thinks so.