Tom,
Now I remember the engines you are referring to. I built models when I was a teenager in the late 1960's. I remember saving enough money to go to the local hobby shop and buy that ENYA for a free flight plane. I used to get Model Airplane News and saw articles about the old engines with ignition.
I also remember drooling over the radio control setups for the then unheard of cost of $500.00, servos extra. I imagine they are cheaper than that today by far.
I've had a box of stuff hanging around for years now including a NIB Sterling P38 Lockheed kit that is a duplicate of one I built many years ago. Maybe someday when I run out of gun projects I'll fly again.
Rob