The 4.21” crank is free horsepower.
I know our engine building friend Mick would wholeheartedly agree.
He thought it was a shame I didn’t put my 455 crank into the mix when I built my 421, but I was wanting to get most of the factory feel of a restored ‘64 421 HO so I didn’t add the 455 crank.
Of course if traction might be an issue the 4.00” crank might be a plus, but realistically either way you go you’re going to struggle to keep from going sideways.
