Gear ratio Choice

[IL_Mach_1]

I have a mildly built 351W in my 1970 Mach 1. It has 255/60s on 15 inch wheels. My son wants a higher ratio but i am thinking 3.5 to keep the rpm reasonable on the highway. However we do not usually go for really long runs. What do you think and what are you running?
Thanks

[1969jimmach]

350s are a good choice. I prefer 325 or 300 to gain performance and economy.and all around driveability.Hope this helps.