I just used sandpaper to clean up the freeze plug holes and put Permatex #1 or 2 on them before driving them back in with a socket and extension..Indian Head Gasket Shellac or Aviation Sealer,High Tack also works well on them..
Don't overlook the freeze plugs behind the flywheel...those can't be replaced once the engine is in the truck should they fail,without pulling the transmission...the one for the camshaft I've never touched on any of the SBC engines I freshened up before installing them..it holds in oil,so they rarely ever rust..
There are two pipe plugs on the block at the bottom,one on each side,they are often difficult or impossible to remove ,but if they'll come out ,you should poke a screwdriver thru the accumulated crud in the threaded hole,I use a garden hose to flush out the block good before installing the freeze plugs..you'll be surprised how much casting sand and goop will come out..
While its nice to be able to pressurize all the oiling passages and engine parts,priming the oil pump isn't always a must,as long as the bearings and other moving parts were well lubed with assembly lube or something like STP or Motor-Medic,or motor oil that wont run off before the engine fires up the first time..but its best to do that if you can,it won't harm anything..packing the oil pump with vaseline was a common thing back in the day to ensure it would prime faster..