I'd build a na 363, not get a ford racing build. You can get more power for your money, though the FMS comes with a warranty.
As for a s/c, it depends on which EFI, the XFI or Sportsman (new) yeah...well, I think on the Sportsman you can.
Who cares how much horsepower it has, all that matters is how fast it goes!
Untested 331, lots of suspension, chewing up corners.