Sounds like you are coming up with a game plan. Make sure when you get motor mounts to use some that move the motor back to the transmisson, otherwise you'll have to come up with custom length driveshafts, move your trans crossmember, etc etc. Dirty Dingo makes a good LS swap mount that helps solve that problem but you have to make sure and use good motor mounts and notch the front cross member to clear the oil pan. I used Their swap brackets along with Speed engineering headers, but if i had it to do all over again I would use the hooker cast headers. They seem to work with everything and provide the best clearance with little to no modification anywhere.
One other thing to make sure when you get your 6.0 either use a TH400 or if you want the OD get a 4l80e, ECU, and harness with your 6.0.