67 GTO Rear End Gear Ratio

[roosky]

I’m restoring a 67 GTO, stock 3.55 rear end too low for highway use. Looking to rebuild rear end (add posi-carrier) and would appreciate a suggested ratio and corresponding tire/wheel sizing. 400 cu” engine getting tooled to about 425hsp. Want both acceleration and 70 mph comfort (not 4K rpm). Thank you, Bill in Oregon

[Whamhammer]

I’m restoring a 67 GTO, stock 3.55 rear end too low for highway use. Looking to rebuild rear end (add posi-carrier) and would appreciate a suggested ratio and corresponding tire/wheel sizing. 400 cu” engine getting tooled to about 425hsp. Want both acceleration and 70 mph comfort (not 4K rpm). Thank you, Bill in Oregon

Personally, I’d look at an overdrive transmission conversion, or putting a “Gear Vendors” unit inline after the transmission.

You could put a 3.08 or something in the rear but I doubt you would he as happy.