First thing to do is pull out one of the old springs and retainers.
Then put the new retainer and lock on the valve (with out the spring). And measure from the bottom of the retainer to the spring cup with the valve closed. If the installed height is too much then add some shims, if not enough then it will need some machine work to lower the spring cups.
Then measure how far the retainer will go down before hitting the oil seal. There should at least 0.060" clearance between the seal and the retainer at max lift.
Then measure the spring pressure at the installed height and at max lift. Also make sure it will not stack at the max valve lift. Give at least 0.080" clearance between spring stack and max valve lift.