What's your best guess?

Actually i like what was recommended. You have lots of cam, gear, and a four speed, so an aggressive timing curve should be fine. I see you have a e distributor so you can set the curve where you want. If you hear detonation, slow it down a bit.
The magnum heads have a faster burn chamber than the old style LA, so less total is needed. I might try 32 total to start with, then see if 34 or 36 is an improvement. If not, and i dont think it will be, i would go back to 32.