Just an update, I appreciate the inputs but in the interest of availability and $ I went with "Edelbrock" versions of Harland Sharps 700016KE, no shims, no adapters, my ARP shaft studs still work, my custom Manton pushrods for the crane irons still work showing 1.5 threads, pattern starts just inside center of valve, centered at 1/2 lift, finishes just outside center of valve with about .060-.070 pattern width. Thanks Cab and hats off to Shanon's for hooking me up.