yetibone is right if you use a displacement that big it won't last more than a few thousand miles at best before you replace something criticle, I've seen a 2.9 lt. t4 that lasted about 30,000 miles but the guy was working on it three or four time a week...
Do your home-work on this one, elektrik, and you'll find something to fit your taste, but ask as many questions you need when talking to an engine builder, like how long should it last, is it driveable on the street, etc. Stuff like that and it should get you by!
John