Well, I have a DynaMite 2800 running under Mach 3 that I converted a number of years ago. At first, I replaced the Dyna controller with the "Ahha" controller (a dos based system to run g-code). After running that for a couple of years, I tore out all the original electronics and rebuilt the thing with modern stuff (a good breakout board, gecko's and modern hybrid steppers). It is a great machine...
For what its worth, I'd suggest taking a deep breath and replacing everything except the power supply and auxiliary stuff (like the spindle brake and front control panel). I think you may have trouble with the original drives (they probably will not recognize the pulses from Mach except in "Sherline" mode).
If you decide to go this route, send me a pm and I'll be happy to send you more details of what I did with mine. (If not, I'd be glad to sell you my original Dyna boards, drives, and motors as spares - I think I have them in a box gathering dust in the shop!)