This is the converson radio, a Kraft KPT-7C Series Eighty. I decided to try the FrSky DHT 2.4ghz module for this conversion. There are a few other candidates but this module is among those designed to be used in this type of conversion.
The Kraft transmitter puts out a PPM signal at a full 9.6v, some 2.4ghz modules (including the previous version of the FrSky) required a signal inverter that also changed the level to 5vdc. There are very simple circuits available to accomplish that, but the current version of the FrSky module doesn't require it.