Hi Theo
There's no reason why they couldn't be fitted to your MX-200s but whether that will solve your problem with your longer irons is a tough one to predict. In theory you should be looking to a softer tip shaft (low kick point) which will give you a higher launch. A lighter shaft should provide a little more clubhead speed as well which will also help. However, if you go too light and too tip soft you could lose some accuracy.
A fitting would be the best way to go (if you didn't originally) or another option would be to look at replacing the longer irons with some hybrids such as MX Fli-Hi.
Best of luck, UTY