Not long ago I purchased from attic of a car repair garage a 57 312  that was disassembled in 1972 to rebuild & all the new  [1972] parts were still in boxes included [All the opened parts wrapped in 1972 newspaper].  The new parts were sealed in there boxes ...There was a New Mellings oil pump in original box .  In the oil pump box is a small sealed envelope with printing on outside " For higher pressure the enclosed spring # M-42005 may be used"    Is there any advantage or disadvantage to using this spring??     Also there is a box of Mellings lifters # J-816-16   would they be as good as the ones available today??   THANKS

Mars , Pennsylvania