I'm going to assume your using ball and ball type pushrods, correct? If so are both ends the same size ball? If not you should run the balls in the proper size seats in the rocker arm and lifters If their the same size5/16x 51/5 ball on both ends or 3/8 ball on both ends then it doesn't really matter other than having the heavy end of the pushrod near the rocker arm instead of on the lifter seat
I put the thicker end of the pushrod in the lifter seat normally on single tapered pushrods with both ball and cup or ball and ball pushrods