Athol Mass. No 4 Jewelers vise with 1 5/8 inch jaws.

Purchased this Athol vise off Etsy and it arrived today. Gorgeous and well made piece with a solid heft to it. Some wear on the jaw corners and one of the jaws has an indent. Planning to clean it up and will be handy to have a small clamp on vice for various small projects. Only history seller had is that he found it in a barn during an estate sale in 1986. Not sure why he kept it around that long. May have been a slow to sell piece until he put it up on Etsy.

Anyone know more about the history of this? Likely decade or year made, significance of No. 4 vs other small vises from Athol being No. 00? And original color or finish? Also, what product(s) would you use to clean off the rust and protect it from more degradation? I like the look and just want to preserve it so I likely won't paint it but want to put something on the surface to protect it and lube the screw mechanism.

Thanks!