Not hard to do a swap; the hardest part IMO was swapping the UCA bushing (it's pressed in and is a pita to pull and and put back in).
The mechanics of the swap is pretty simple, disconnect the driveshaft, unhook the brake calipers, discconnect the panhard bar, shocks, lca's, uca, and it'll come out.
Before putting in the 8.8, you might want to put in different gears while its out. And depending on the 8.8, you'll likely need a different pinion flange to bolt up to the V6 driveshaft.
Depending what your goals are, the 8.8 might already be strong enough for you. But if not and you plan on building it stronger, you'd probably be ok just building the 7.5, using a detroit true-trac instead of a t-loc.
There's lots of posts about 8.8 swaps in various forums online, too.