I keep thinking about the Chevy crate motors and what a RamJet 502 would do in an H2. I know you would have to have a custom exhaust and oil pan because of clearance problems, if their dimensions are correct and the front steering would probably have to be modified and custom engine mounts, but OH WHAT TORQUE -565 ft-lbs!
I helped my son shoehorn a 454 Chevy crate motor into a 1965 Chevy Nova - it took a year and half and a lot of cussing and fabricating steering parts, oil pan mods, frame rail modifications and lots of cussing, but the finished product was worth it.
http://gmhorsepower.com/Ram-Jet-502.php