I would think that would require the least re-engineering of the car. Find a GXP
and use everything including engine, transmission, all electronics, the entire fuel
system including fuel pump and probably front drive train including axles and
suspension. You are basically rebuilding a car so you'll also need copious
amounts of skill, money and time. If that's the sort of project you are looking for
and you have all those things you'll eventually have what you're looking for. If its
simply a performance car you're after, buy a GXP or even a GTP and motor on.
You can easily do upgrades to those cars while at the same time driving them
instead of having to wait several years for a project car to be completed.