Axles-Gears-Powr-Lok setup
RRR already got the powernloc. There is other info necessary for part of your question though. What transmission and cam are in your car/motor? Sometimes that much of a gear change with the wrong cam will make a your car a dog. I did the same thing, and sure as **** I was putting the 391 back in a few weeks later as the 323 were not happy with my cam…