How tight is too tight. 512 stroker rebuild

I assume you did oil / lube bearings/ cylinders at assembly? You could "park" that thing 5 years and the oil would not go away. Rust is another matter, but if the engine is sealed up that should not be an issue. ANY idea what the turning force actually is? My first thought is that you are imagining trouble.

So far as priming, I always start with NO FILTER. This is because the filter is directly after the pump output, and removing it removes any "head" that the pump must work against. It should take about 1-2 seconds to get oil out of the filter mount. Then fill and mount the filter, and I like to remove the oil sender, hook a hose to it into a can, etc, and prime until that gets oil. Then rotate engine slowly (I forget the degrees relative to TDC) to line up the cam holes and get oil to the rockers.