You do have a little wiggle room on your push rods if you installed hydraulic rollers like the comp cams 856's or the "Hell Cat" lifters. Having not decked the block or heads also helps your case. You can usually tell if your push rods are a bit too long because it will sound a bit more intense during idle but most people end up finding out when their push rods destroy the lifter's push rod seat and the rest of the lifter's internals.