Just my opinion mind you but why not stay with the flathead 6 and soup it up like these gents did.
This is Pete Anderson's 230 L6 with dual intake and exhaust,high compression head and a mild cam.
Or Don Coatney,s souped up 251 DeSoto with dual in and out and a mild cam.
Or like I did. A Chrysler 251 fit in my 52 1/2 ton with very little mods and has plenty of power compared to the original 218.
As soon as I bolt this stuff on I'm gonna be the coolest guy in my neighborhood. Oh yeah.....I live way out in the sticks.