We just did this with a FM1000, you'll need a whole new wiring harness, new sensors, and a Field IQ for the 750.  It will give you much more accurate population information than the KPM did, though.  For example, the KPM would tell us the planter was planting 36,000 - just like we set it, and Trimble would show us that we were planting 3% multiples and 3% skips, so only had 94% singulation (had to slow down.)