How do you want to run the boat? Loaded for fishing or more towards top end running?
If you're looking for a good, safe setup..... then set back around 8",10" or so (I wouldn't go past 12") .... propshaft about 1/2" below the pad ...... a good 26 or 28 pitch prop...... either an overhub exhaust like the Triton or an overhub/thruhub like the one Todd makes at Hydromotive. Todd makes some great stuff for the Allison, but so do I !!!!! This should be a good all-around setup for running loaded. If you're looking for the big number, then you'd run the engine higher and slightly bigger props and lighter load.