Your engine No. is a big mystery to me. Looking in the book “The Scott Motorcycle” by Jeff Clew for information didn’t really help much. Your engine No. doesn’t seem to apply to anything.
PY is a 596cc Power Plus Replica engine made in 1930 to 1932.
56 is odd. 1927 No’s went from 9656 to 10096 then dropped to 601 for the last one.
Suffix M was used for a short while in late 1927 on the high numbers.
Suffix A was used on 601 and in 1928 on 602 onwards but not on Replica engines !
M was used on some works engines but 56 doesn’t tally with anything.
Have you got an old log book for the bike?
Sorry I can’t really help you.