Or you could join Inliners Int. and as a member write one of our technical advisors. The old hop up books are ok but a few things have changed in the 50 plus years since those went to print. The 12 Port News has had many articles on building the 261s, some of those are still available in the back issue stash.
Best of luck.

It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed