ball and cup pushrods size for a 360

Make or purchase a pushrod measuring tool, mock up your engine, measure the required length and order from the manufacturer of your choice. Be sure to let them know what spring pressures you're running too.
This is correct as no engine is the same once modified. m/p sells a checking pushrod and make sure your valve tip to rocker tip is right also. some shafts have to be shimmed at the pedestals to be right. my rb required .050 shimming under the shafts with indy ez heads.