The stock 235 rocker arm ratio is nominally 1.5:1, same for both intake and exhaust. The 216 is nominally the same, although I calc 1.48:1 from some old published data on cam and valve lift.
I have an old, NOS set of Fenton high lift intake rockers I picked up, years ago. Never tried to install, since the set I have is the Powerglide-specific PN. They had a different set for standard transmission cars, and presumably the difference was for hydraulic vs solid lifters. Image is from the instruction sheet. I don't see the spec on the instructions, but the Fenton box says the rockers increase the valve lift by 0.065". That calculates to just over 1.7:1 rocker ratio, depending on what cam info I use.
So, your seems like you brainstorm is on the right track, especially if you can improve exhaust breathing. Interesting the old Fenton parts don't include improvement on the exhaust side...
Edit: I see while I was typing, the factory data at 1.477:1 was published. Thanks!
