Aftermarket heads. RHS Pro Torkers. 350 SBC. hydr. flat tappet @.500 lift cam. roller rockers. 7/16 studs. My valves are +.100 longer than stock. WIth a solid lifter a +.100 longer pushrod put the pattern right in the middle of the stem. With a hydr lifter a stock lenght 7.80 put the pattern right in the middle of the stem and with the +100 it was way to the outside. My plastic length checker puts it at about +.050. I would think the stock length 7.80 would be correct? It shouldn't be this difficult.