Welcome!
Very cool project you have there. The 5.7 is a great engine. As far as the alternator, you should be able to rig one up fairly easily, but it will need to have a serpentine pulley on it. I made my own bracket and mounted the factory alternator out of the way of everything.
If you need to buy a flywheel and clutch setup for your transmission, let me know. I have a brand new flywheel and clutch for a 5.7 that didnt work on my project. The flywheel is really expensive for these things. I wont charge nearly as much as new. Let me know if you're interested, I would sure like to see them get used!