225 Slant six Rocker Arm Adjustment Screws?

What's wrong with the ones you have? My 1964 vintage ones work just fine and hold their adjustment. If you used white tape, basically teflon, its going to exacerbate the problem.
A couple years ago, Comp Cams had them. IIRC, they're a little longer than stock but leaves enough room for thin lock nuts on the top.