I'm not sure what's "stock" but you don't have stock, you have a crate motor. So, for you it's the 5/16" ones that match your push rods & the rest of your engine.

70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"