my boss and i are building a 66 shorbox shop truck. we bought a good running late 70's 460, we put DOVE-C heads on it with cast rockers #r1033.spe,comp thumper cam, pushrods are #rp3164, torqued rockers 25 ft lbs, one of the rockers is still really loose and has the same pushrod as the rest, and noticed that the lifters are riding half way on the lobes is this normal and are they the right pushrods?

 

You have to check push rod length. You can buy a checker from Summit.

 

The position of the lifters is ok, they will ride half on/half off the lobe. As for the rocker being loose, since you are using a stock replacement rocker and pushrod, I would say that you have a lifter that is still collapsed, allowing some looseness to show up. Have you tried priming the oil pump and see what happens once the lifter is oiled up?