If you truly have a .001" press fit over 10-12" of 5/8" pipe, you will never get it in there. No way. I need several tons of pressure in a press to make that .001" fit go an inch deep without heating the female part. Aim for a line on line fit because non of this pipe being pounded in is accurate or round. I'd rather have it go in a little loose and then swage the end and at the lifter bores to seat it.