7.25 to 8.25 swap? /6 to 318 swap?

1970Duster yes the previous owner also swaped the front to the single piston front calipers also, and thank you I now know why he did that instead of keeping the 4 piston ones. This is my first mopar. I agree with the use of a prop valve but I figured I would ask you never know there might be a mopar prop valve out there that would work well and look factory!