273 questions...a few of them

Ditto on the small block balancer. It is ~90 deg difference between early and late crank dampener marks, but I don't know if exactly 90 deg. Early ones are with a cast-iron water pump (64-69?) and later are with the aluminum water pump (70+). I don't know that the dampeners interchange. I read somewhere that later ones are thicker, and some after-market ones are thicker still, so that could throw off pulley grooves. May also be balancing issues. Since I changed to the alum water pump in my 65, and later timing cover, I just cut a new timing mark in my original dampener.

Good info about where to set the crank when adjusting valves. I always set the piston at TDC and ASSumed the cam would be on the base circle there. Now I find not always true. I put a hydraulic cam in my 65 SB (w/ adj. rockers), so no concern since that is just for the pre-load set. My Mercedes diesels are ohd cam, so I just put the lobes opposite the lifters. Strange that different solid lifters would be different heights. Is that measured from where the push-rod sits?

Check on the slant six forum. Those are also solid lifters, and many slanters adjust the gaps with the engine running. I wonder if similar could be done with a 273, but maybe they sling more oil.