How fast are you looking to go and at what weight. I’m betting the ET difference between a 4 inch crank and the one you are looking for isn’t worth the added issues. Gotta make sure the head is big enough for it too.

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time