Wish I could help you, but all I can tell you is that I have this engine in 3 different sizes. Would be interesting to know if yours is the same as one of mine or a third size...
Paint looks pretty good on that one, nice burner too 
Well the boiler diameter is 2 1/4"x 6" long, flywheel is a 4 spoke with a 4" diameter. Did the video come through alright?