I now own this mower, but do not know how old it is. Can anyone help. I sold many in the 60’s, but now am unable to decipher the reg no, to tell, like I used to. It has a BSA Sloper engine, the machine reg no: MK4 DC887. Engine No: RS119B 2785 K. Has an Amal carb, 379/120. Can anyone help?.