Tony Eifflaender won the 'Gold Trophy' at the UK NATS several times in the 1990's running PAW 35s and 40s.  Other than myself, I have only known of 2 other individuals to use diesels in stunt in the US.  I did so briefly when I started in 1992 and also later in some 1/2A and A size planes.  About 10 years ago I planned to build an Eifflaender 'Freebird', powered by a PAW 40.  I purchased the engine and plans from Tony, began construction and engine break-in.  This project was soon put on the 'back burner'.  I had parts cut, basic wing construction and partial break-in of the engine.  Now being retired, I thought I might resume the project.  So I dug out the engine did a bench run.  I lost my starting technique with this engine so you can laugh at my incompetence 
Fred

The PAW diesels I have are all easy to operate.  I would advise using a wood prop on the bench.  It's safer that way!

Most often, the contra-piston will not come back up unless it's running.  A piece of fuel tubing on the screw will keep it from "unwinding".

Floyd

Most PAW contra screws are close to a common SAE size. I seem to recall 10-32, but that may be far off.

I've made lock levers for several of my PAWs. Find the US Standard (or NF if it is that) close to the PAWs comp screw thread. Cut a piece of common hardware store 1/16" aluminum so you can file, or whatever, it to about 1" long, with a 1/4" "shank" and about a 3/8" circle. Roughly 'O=' kind of thing...

In the center of the circular end, drill the tap drill size, then tap the hole with ONLY the tapered  entry portion of the tap. FORCE - yes, FORCE the engine's comp screw into the barely started threads. It is sturdier steel than the 56S hardware store aluminum, and WILL force the threads through to match the comp screw.

Now, the only change in operation is to make sure the lock lever is free enough to allow starting adjustments and to snug it down once the desired setting is attained.

I also have a 40TBR and have benched it occasionally. Aside from the engine's weight, and the uncertainty of filling the tank for sure cutoff within the alloted time (8 minutes for USA AMA; 7 minutes for FAI F2B), it looks like a strong horse for the job.

BTW, I usually wait a bit longer for setting changes to settle, except when obvious over-comp occurs.

On smaller PAWs, I've found that a starting drill of noting the number of drops into the venturii that does the job, and the number of times to pull the prop through before serious flicking, usually gives a consistent and  quick restart. (If you are using a diesel in stunt competition, forget going onto the circle with a cold engine. Warm it up first, and preferably just before you signal judges to start the clocks.) With a warm engine and a dependable starting drill, you won't need to fiddle comp or mixture. It will come up on song and ready.

BTW, again, most PAW 19s are at least a match for a Fox 35 on a profile CL model like a Ringmaster or equivalent. Different fragrance... less fuel consumed... solid all the way!