How much of a budget and how much do you like your GT? If you really want a GTP then it could be cheaper in the long run to sell your GT, buy a GTP then go from there. I know it sounds dumb but doing a swap properly may acutally push you past the price point of just buying a GTP outright.
Parts can be had cheap, yes. But machine shop time to check out heads, repair any damage, coolant elbows, S/C coupler (if needed), gaskets, headers, injector o-rings, a GOOD ECU TUNE, trans. swap (because the GT trans will break eventually under boost- not if, just when) all cost extra $$$ above the actual parts to swap. So say your GT is worth $2K. Say you spend another $1,200 total (including all labor) to accomplish this. Can you find a decent GTP in your area for $3,500?
Just throwin that thought out there.
And DSM?? If your budget is tight now for a GP, then I wouldn't bother with that route, lol...