What's the valve lift for the combo you're planning? Solid lifters I assume.
I would do all the seat R&D on some scrap 318 head to figure out what works. While the 920's are a little better than the later stuff, the port layout is very similar, so whatever you find works on the later head should also work on the 920 head.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
