Oil Priming on a 340

Yup. Pull the drive with a big flat blade screwdriver and a pair of long needle nose pliers if needed.
Insert the priming tool (mine is a cut-off drive and pushrod welded together).
Turn clockwise with a hand drill.
While turning the pump, have a Buddy turn the engine over slowly two full turns or more to align the passages to get oil up to the valvetrain.