I would suggest that you keep the L67 and 07 GP separate, just because you could probably find a complete L32 for cheaper than everything you would need to buy and modify to make the L67 work in the 07. The L26 is damn near bulletproof, especially if it's been taken care of. So that L67 would sit for years and years before you even started thinking about swapping it in.

Find a nice, rust-free 97-03 with a blown engine or trans, GT or GTP, and swap the good L67 into that.