I'll probably get "Spanked",but I'm going with what "Patrick's Antique Auto" states in their parts catalog. They say that there are no decent aftermarket (Hydraulic) lifters for the full-pressure 235/261's. They strongly recommend solid lifters,which,in turn,may require different push rods. This is the route I took,when i had my head rebuilt. Oly's valve adjustment,(in "Tech Tips") is a GREAT way to adjust your valves,with only two different crank positions. Good luck.
