Hi David - how does one get from North Carolina to Bendigo?  Welcome.

Fair enough on the 15khz output - I'd imagine the internal CRT assembly to be significantly different then.  Just noticed though the price has dropped significantly on these VGA --> 15khz "arcade" adapters though, which gets me thinking of a breakout box ...

http://www.ebay.com.au/itm/GBS8200-GBS-8220-ARCADE-GAME-Video-CONVERTER-CGA-EGA-to-VGA-to-LCD-Latest-/261542747683?pt=AU_ArcadeMachineAccessories&hash=item3ce5299e23

JB