I got some circa 1973 SB solids still in the 2 boxes. The instructions spec for oil type said, "as of 1973, the oil marked..." Though that was a good indicator on how old the lifters were, or at least the printed instructions...
I just measured the base of a tired 318 cam and an MP purple cam (unknown spec but I believe its a 340 resto cam)and the base circle was .072 smaller on the larger camshaft. So without a pushrod or rocker change, thats larger than the .060 preload recommended for hydro rockers...enter adjustable rockers. Case solved...