Hello again Julopva,
Your engine number CA10-822 tells me that it is from an early 1954 swinging arm Golden Flash. In fact it probably is the same engine that was fitted when the bike left the factory. Is so, as the numbering system started at number 101, yours is probably the 721st S/A Golden Flash that was made. A nice find indeed. It was available in Black or Gold (BSA Polychromatic Silver Beige).
If you are interested, the UK BSA Owners Club will be able to confirm this, tell you the original colour, the actual date it left the factory and which dealer it was dispatched to.
As you can see from the above pictures, this was a very handsome bike. It would be good to see some pictures as it is.
Beezageezauk.