I built my 312 for 5500 rpm duty in 1963 (ported heads, full race cam, milled heads, forged pistons), refreshed it in 89. This summer I brought the top side fully up to 650 cfm capability. 

From test driving, its clear I need to bring the bottom end up to 6500 rpm duty to match the new found top side behavior. I'll be replacing the 50 year old ECZ rods, 44 year old TRW pistions, adding the longer main bolts and adapting an FE Canton screen. 

The only question I have are rods. Are C1 rods good to this duty at 10:1 compression naturally aspirated?

Comments/suggestions please.

Thanks