340 6-PakThe 340 engines are legendary for the power they made. Designed for Trans Am racing, the little motors were known for high winding revs. It seems there is an almost endless supply of small block parts, and recreating a 340 Six Pack wouldn't be hard to do.
500-6Visually recreating a 440-6 is a no-brainer. Sure, you can find a used 440 block, scrounge for a steel crank, get the good rods and dig around until you find a decent set of usable heads, but you're still using old parts. You can even open the motor up a bit and stroke it, but are you going to get anywhere near 500 inches? Affordably? With that kind of power? Probably not. Just imagine how much fun you'd have with 500 inches and 545hp sitting under the three deuces!