Hello Mike
Reference sources place your rifle as a 3rd Series example dating to late 1936 or early 1937.
Most collectors frown on refinished air guns unless the cosmetic appearance is extremely poor. Refinishing is of less importance to those who just like the rifle and would intend shooting it on a regular basis. It would however affect the resale value and I doubt you would recoup the cost have having the refinishing carried out.
Hope this helps.
Regards
Brian