I don't use one, but just from google it looks like they recommended an adapter and the original bracket. Edelbrock says the adapter 8015 was designed for 1968-71 Pontiacs, and 8014 for 72-76. Both are in stock at Summit, but there's not much to them. You could make your own if you have to.
I can imagine that your real problem would be finding a 1972-76 original bracket. Is that what you're really missing?