I think I used the PAC 1226 or 1326 roller springs with Comp Cams tool steel 10 degree keepers for 1.500 diameter springs, I set every spring up so they are between .055 to .080 from coil bind which I think gave me 275 lbs. on the seats and around 750 lbs. opened. My heads had been ported al the way to the valve seats and they had all the numbers for the later Victor castings according to the tech. I talked to at Edlebrock about them.
No real challenges on them that I remember now, that was over 6 yrs. ago and many motors builds since also