Pushrod length question-Magnum engine

Is the .512 lift based on the 1.6 magnum rockers or the more typical 1.5 ratio rockers? If it's based on the 1.6 ratio magnum rockers then you should be OK with .512 but certainly check clearances. I am running .509/.512 without guide clearance issues, the general accepted number is .525 on a magnum head before the need to cut the guides down.

You will need to measure what you need for push rods and will likely need to order custom length ones.