dr-bowtie, I am glad to hear you comment on this since I recall you first alerted me to the potential problem of pushrod rubbing in the stock holes, but your comments here are confusing to me. Specifically I have the lowly 883 heads on a 350 and the cheaper type of roller tip rockers from Speedway. I have both 1.5 and 1.6 ratio rockers and I would like to run the 1.5s on intake and 1.6s on the exhaust without elongating the hoiles and using stock rocker studs. I have 1.6 ratio rockers on all the valves now with standard height covers and rotating by hand I can hear no contact with the covers. In your post above you say there is no need to open up the hole except if you use screw in studs and guide plates with lift higher than 0.450. From what you say I should be able to use the 1.5/1.6 combination with no change to the heads?

Don Shillady
Retired Scientist/teen rodder