alright, i'll chime in before the bike engined guys poisen your mind :lol:
yes, it's been done. I have an LS1 in mine, and I LOVE it. Believe it or not, my car actually does go around corners . I have done near zero chassis tuning, and still have some chassis problems to work out, but the car is respectable in autocrosses, even with my ruler based alignment and worn out tires.
I don't know how much a Ford 5.0 engine weighs, but I'm pretty sure it's an iron block engine. Even with aluminum heads, you'll probably have a 90 lb penalty compared to an aluminum block V8.
I had a Rover V8 in mine to begin with - very light, but not much power out of the box, and expensive to mod.
I switched over to a 5.7L LS1, with AFR heads and a mild cam. She puts out an easy 440 hp, and can idle along all day or cruise at 1400 rpm @ 70 MPH with no problems, or blow away the tires at 60 or 70 mph - and will last a LONG time in this car.
If I were you, I'd aim for an all aluminum V8 with pushrods. They're light by V8 standards, and don't take up the huge amount of room a comparable over head cam design would. Also, make plans for what you're gonna do when you decide you don't have enough traction. My current solution is 305 R compounds in the back.
My car is not a Locost - It's a Rotus. Rotus is one of the bigger and heavier seven variants. The lightest one I know of, with a stripped down rotory engine, weighs 1525 lbs. My car, after the engine conversion weighed 1670 lbs (no gas in mine - not sure what the rotory powered one had when it was weighed).
If you are careful with your choices of engine and transmission (my tranny is a pig), I'm pretty sure you can weigh in at 1500 lbs with a V8 drivetrain.
I have to tell you though, even with spirited driving, the V8 will not make you much faster than a typical 200 hp seven, or a busa powered seven.
I've gone driving with a few buddies who shall remain nameless (a certain person with a SVT Caterham, and one with a Busa powered car), and as long as the speeds are somewhat normal, things are traction limited and the cars seem pretty equal.
Like anything else, the shove you get when you squeeze the pedal is addicting, so I don't feel like I can give it up now. The bike engined guys will tell you the same about the sound and feel of their high revving [cough]squirls[/cough] er... i mean engines :jester: