I take it you're using a hydrollic cam, the pushrods you have will more than likely do just fine, but if in doubt, with the cam in place install an intake and exhaust pushrod and roll the motor through check for the height geometry. If it doesn't bind up at full lift then you'll be just fine. I built a 428 that was running stock pushrods with a hyd. cam that has 633 E and 594 I with no problem. I opted for a set of roller rockers just to get a little more out of the motor.
Check with your local machine shop "if you're not sure" and they'll set you in the right direction.