I do question using these old obsolete engines in a nice airplane. The engine I showed didn't run correctly and nothing I did with it instilled any form of trust so it turned into a parts engine. I like pumpers and ended up with a new OS 120 III and loved that engine until the day the pump went out. I paid the big bucks to send it in for a new diaphragm first then discovered the pump required replacement so moved on instead of sticking with the OS. I went to YS and haven't had any problems in years. Once in a while I need to replace a diaphragm but they only cost $2.50 and keep spares on hand for the two different sizes I have. 1.20s and 1.10s.
At the moment with most modelers going to either gas or electric I find a lot of both brands of glow engines for sale at swap meets for next to nothing. I gave up buying new four strokes years ago, they are too easy to rebuild to bother with a new one at this time.
For about $100.00 you can also buy a new .91 SK two stroke, I have also had great luck with these engines.
I wouldn't risk a plane by using one of these old engines. They do provide me with a number of screws and sometimes help others out by using them as parts engines.
If you need a pumper then try the swap meets and pick up a YS but make sure it is an FZ model, I have a number of the older models but unless you have been taught to tune one the older models can kick your butt.
I have also found a number of like new, even some NIB OS engines without the pump that are a great deal.
There is no good reason to be fooling with these old obsolete engines and risking a nice new airplane.
One of my hobbies is rebuilding OS and YS engines and I have done a lot of them. When I have a question or problem the first thing I do is ask BAX if it's an OS or read the YS forum when needed.