The number he gave you looks like the casting date code. G = 7th letter of alphabet = 7th month = July. 13 = 13th day of month. 4 = 1954. Should be full pressure motor. It should have all of the visual clues as well: valve cover held on with 4 screws, low side (lifter) cover, no little plate & pipe thing on driver's side of block. Good luck!


Professional Novice