Thanks for all the responses.
Unfortunately the few images I got in the shop are junk to try and work with, out of focus, etc. But I will post a few of them here. Since I chose not to buy the rifle I will not bother blurring the serial.
Yes, the serial seems to be reworked, but it is done nicely, this is not some grind and electropencil job. As for regs and serials, that becomes an interesting question, particularly when discussing firearms that were produced long enough ago to have never required (by law) serial numbers.
T!