Bill,
Wrote a rather lengthy reply, but the send button blew it away.
Anyway, good to see you back.
Fuel mix is equal parts of Castor oil, Ether, and Kerosene known as Olde English mix. You can add 2 percent Amsoil DII if it helps starting, but my original 1950 era .049 didn't need it. Best prop is a 6X4 or larger, as you don't want to over rev the early models as they were said to have a weak crank. I've run three of them, with no problems at all on that mild fuel mix, but I really think most of the failed cranks were caused by over revs, and/or over compression.
Standard size #10 O-rings from any plumbing source stand up very well, compared to the short life original McCoy O-rings. There are even better compounds such as Nitrile O-rings if you think you need them. Even the original rings lasted for approximately a half dozen flights on my Firebaby with the balloon tank of unknown capacity.
The second model McCoy .049 diesel with the venturi insert, and beam mounts was both more powerful, and reliable than the original. I have one still new, but have been very happy with my originals, so it remains unrun.
A Goggle search should find reviews for the Duraglow, along with parts lists, etc.
Hope this helps.
Bill