Radios are all over the place. There is not one consistent brand really unfortunately. It really depends on how fancy you want to get, or you simply want to replace the Heng Longs with a hobby grade radio.
Tamiya/Futaba Attack whcih comes with the full option Tamiyas, Spektrum DX6i, Turnigy 9X/9XR Pro would probably cover over 80% of all the radio used by club members.
Basically any 4 channel radio would give you all the functions on the Clark. Additional channels can be use for other things.