I looked into this for my 1970 Plymouth Satellite, as I was upgrading the 318 to a 440. I thought a 4 speed would be awesome and make the car more fun, more rare, and more valuable. Well, it certainly would have done all those things, but my goodness the cost. I'm in Canada, so using the Brewer's kit, which doesn't include the tranny itself, plus machining the crank for the pilot bushing, was over $10,000. I just can't justify it. I spent $2500 on a rebuilt 727 and 2800 stall, and it is absolutely fine. Just my two cents. I do most of my own work, but this was too much. If I ever build another car, it will be a manual for sure, but it's just easier to pay the extra and start with one usually.