Hi Ed
I've just dug out the drawings for the Sun. I also have a completed engine, although I cannot take any credit for making it - it was made by my late father. The drawing is old - issue date is 1956 and I don't know if any changes were made to the design of the castings over the years since then.
If you are still looking for the drawings and you think these will be useful then I'll be happy to scan them and e.mail direct to you. Also, if you have any questions about the engine I'll do my best to help by examining the engine.
Regards
Mike