Yes, there is a reason it won't work. The G320 needs a power supply with a filter capacitor because it is a Pulse Width Modulation type controller running at a fairly high switching frequency as compared to the SCR type controller you linked. You might get away with adding an external capacitor, but then again, you might not. These KB drives work well into resistive and/or inductive loads, but aren't designed for driving capacitive loads. If the regulator gets unstable it could fail due to high current draw charging the capacitor initially if it does not ramp the voltage slowly enough. It could also damage the G320 if the voltage overshoots above the 80V rating of the G320.