After reading the original post again, I may have a little more information to contribute. I bought a 61 Speed13 for a fast airplane scratch build project. I built the plane around the engine. After some initial problems with a machining error in the carb, the engine is a powerhouse. I got the 10mm carb option since I wanted top speed. This airplane has the engine mounted upright, and with the header in place I can not get the tank high enough. Mine has fuel draw problems. The obvious solution is to side mount the engine, or use the smaller 9mm carb which would be a better choice for a pattern plane. I put a pump on mine, which also works. The next plane I build around this engine will be side mounted.
I have about a half gallon of break in fuel through mine.
10 to 15% fuel is fine. I would not use less than 20% oil, but that goes for all of my engines.
Novarossi says use only their C6S glow plugs or you void the warranty. They work fine so I use them.
The 50400 pipe is very quiet, but good god is it heavy!! When I weighed one (a while ago) I think it was 5 or 6 Ounces! Yikes. I made a carbon fiber pipe for mine, but I think a Macs quiet pipe will work at half the weight.
I am setting mine up to run in the 17K range, but other projects have been pushed in front of this one so I don't remember what props I was using. Since I am going for speed, they are small diameter and high pitch. I will dig out my notes if anyone is interested.
Leo at Klasskotemo and Allen at Planethobby are the experts on these things, they sell them and will help with any questions or problems. Great people to work with.
Scott