Really olds needs aftermarket heads and oil mods to run above 5500 for very long and there heavy, same with buick except for the 430 wildcat motor 10.5 from the factory & with good heads but hard to find 'came in 67-68 electras'
So for the sake of head flow and good early steel cranks the 351 ferd I guess, but I still think I'd be on that bus with someone else we know.....