They are blueprints, which means they have material callouts, and the dimensions the parts need to be to fit. There aren't any instructions. I think you can probably find build logs on-line somewhere. Also, you can check into the Edgar T Westbury engine that is similar (4 cylinder and I think it is also 50 cc. capacity)
Edgar T Westbury was an English Engineer who wrote about small engines for many years. During WW II, he designed a few small steam engines that were supplied in large numbers, to the resistance forces in Europe, to be used to drive small generators for radio messages. (Gasoline was unobtainable unless you were Nazi military, and those guys were not sending love messages to Britain. ) Everyone had plenty of wood laying around, so you could go off in the forest, stoke up your little boiler, and send your radio message, then dump the fire, and clear out of there. (The Nazis had radio interception trucks that they used to locate transmitters, and they got VERY good at it, just driving around. . My understanding is that all of the ETW engines with star names, were those designs. (Polaris, Sirius, etc.) Some of them will run at 4000 and 5000 rpm. They are quite amazing. No one knew this until after the war. He released the designs to magazines such as "Model Engineer" during the war, but they were actually designed at the request of the British Ministry of Defence.
Anywho, the point of this is that if you can find a build log for the ETW engines, the procedures would be exactly the same, and just because the parts are a little different does not matter. The instructions are mostly how to avoid making mistakes, and they apply to all small engines, whether gas or steam.
I will go down now and see about getting them copied off. I will be in touch on here with what the cost is. It should not be that much.
I still have my engine, and I am about 25% of the way towards completion. It has been sitting for a number of years, and I think the Covid-19 situation is a good excuse to spend more time in the shop.