Good morning. I have an early ford 302 with 5/16 pressed in studs, 1.6 ratio, flat tappet hydraulic lifters. I am confused as to what size pushrods I need for my engine. I have been told the correct ones are 6.272 for flat tappet and I have been told that i need 6.750 for my flat tappet engine. And that the size listed for either roller or non roller are reversed.....