Ideas on what's causing my click/tick/rattle noise?

If you swap
cam, lifter, rocker shaft, rocker arms, and pushrods
The whole thing can swap between solid, and hydraulic systems. The only "gotcha" is the rear rocker shaft bolt. Need to use the correct bolt for the head (changed sometime in the '70's). As stated by Volaredon, some times it is necessary to enlarge the lower rear shaft bolt hole (when using a late shaft on a early head)
The difference in oiling, is the cam, itself. The hydraulic cams have a groove around the rear cam journal (not the bearing). The solid lifter cams just have two intersecting oil holes in the rear cam journal.
PS: Some aftermarket solid cams are being ground on hydro blanks and have the oiling groove. I always groove the rear journal on solid cams, in my engines. If I wind up with too much oil up top, I can always put a restrictor, in the oil passage in the rear rocker stand