I have only used turbo plugs from OS an Merlin, and these are interchangable. The threaded part is a little longer on the Merlin while the conical part is the same.
There are lots of options to choose from, and the only ones to really stay away from I would say are the ones that use a regular plug, They can be made to work if the head volume is right (the Mecoa ones needs modification in a lathe) and the threads of the glow plug are sealed below the copper washer with Hylomar (or similar "form a gasket" stuff).
If you have access to a lathe you can also make you own turbo heads. Either from an old plug or as an insert for the stock clamp ring.
Below is a little line-up of heads I did for another thread on this topic. Starting from the left we have the stock Cox (low compression), Mecoa for a regular glow plug (an Enya #4 plug is in there now), a regular Cox head converted to Turbo (by me), a Valentine dedicated Turbo head and finally the Galbreath Nelson plug head;
And here is also a turbo head I made from a stock cox .020 head, the plug is only hanging on by a thread or two (!) but it works:
