if there's a problem it's more likely valve seals, but after you've put oil in the cylinders it can take a fair while at high rpm's to get it all cleaned out - check if compression is decent, and is even on all cylinders - oil filter not too important - nice, but your's made it 50 years w/o one
if yer gonna rebuild, may as well take the freebie and start w/ that so the truck still moves til the engine's ready - if you plan on having the truck for the forseeable future, scoop that free core anyway for a spare - they're not makin'em anymore!!
Bill
