roger... 2 valve covers = dual overhead cam 24v. If you're seriously thinking 5m, you might see about importing a 6m from japan instead of rebuilding the 5. The 6m has a larger displacement (3.0L), but is basically the same engine. The six has less emissions junk, but can easily be converted back to spec with the 5m parts.
I also have to mention the 7m. There's lots of info out there on this swap, so I think you'd have an easier time making it 'faster', and it's more powerful than the 5m.
Alas, I am still a sucker for technology, and whenever possible, I prefer to modernize the vehicle. So I'd vote for the 3rz. Better yet, rebuild the 4cyl with a turbo, or convert to hydrogen or CNG, check out the toyota diesels, or even a 5vz.
good luck with the swap
