I would do a frame up resto, but instead of the gxp frame go with a custom Y-body. Do a motor swap, something like an ls6 and get some IRS.. something like the corvette c5 irs system. Once you're done with that put a body kit, something like a corvette body, maybe even the Factory 5 GTM Supercar body. Maybe a t-56 transmission? tr6060 even. That would be my idea.