There is nothing wrong with a Muncie trans especially the M-22. I assume you know how to shift. I've had a few of them and never replaced a clutch, transmission part, anything. You just have to know what you are doing.
I blew up a M22 behind a 454 in a Chevelle going into 3rd gear and I knew what I was doing. Over the years I've abused the hell out of 18 spline trannies, all behind BB's, and they just keep laughing at me, saying is that the best you can do.