170 or 225?

I have the original 170/903 combo in my 64 Valiant. I have a good running 69 225/904 that needs a home...170 needs a rebuild. Should I stick with the 170 or go ahead with the 225?

NOT going to put a V8 into it, so skip that suggestion.
I would drop in the 225 and keep the original 170 on the side. If you plan on keeping it a three on the tree you just need to swap the flywheel to a larger diameter center to a slant six 1968 and up manual flywheel. With a super six and that a903 gearbox you should be churping. I'm pretty sure your rear ended ratio is a 323.


And in the future you have the set up already to convert to a four speed just need a hump and shifter with linkages.The first year four speeds are the best 3.09 first