Splayed low seat jesel tool steel .905 tie bars in the 636, and cam fx .905's in the 660. 1/2" intake, and 5/8" exhaust pushrods.

I had to choose between tappet dia, and lifter bore spacing. I went with highest quality small tappet, with the widest spacing I can do with the blocks I have to work with. My push rod spacing at the tappets is 2.3. That's about as straight as I can get them. I'd do .937, 1", or 1.062' on a 60 mm core if I were planning to zing a smaller CI combo.