Finally getting around to doing the PSU conversion, I ordered a 400W PSU, didn't have stock so they send a FSP500-50FDB part as a form, fit and function replacement.
Just looking over the wiring connections to adapt to the MMD, the 24 pin connector is short of two 12v (yellow) and one ground wire (black), there are plenty of auxiliary connectors on the PSU to tap into thou, my only consideration is the 3.3v (separate orange and brown wire) sensor connection at position 13, I'm inclined to connect to MDD position 6, but i don't really know what 6 is connecting to, just wondering if there would be a preference between 6, 17, 18 or 19?
Update, as it turns out position 6 on the mac connector also has aditional sense wire (thinner orange wire), I wired this wire direct to the brown wire that is connected to position 13 on the FSP connector. I inserted a connector into the FSP loom disconnecting it from position 13.