I had my hands on one the other day checking it out I noticed that the plugs are larger plugs compared to the standard size found in smaller engines like the Wasp .26
A friend of mine got one for his buggy and as we tried breaking it in, we went to switch glow plugs with a spare new OS #8 he had and it just pretty much dropped in the hole til we compared the thread sizes and found out the original plug was much larger. So if you get this engine, be prepared to spend on a completely different glow plug than the rest of your engines use.