It will probably cost you more to find one and have it installed than the piece is worth. They were made on the low side of quality to begin with.
You will need to see a gunsmith.
Impossible to answer without a detailed description of ALL markings, bbl length, type of action, caliber, box, papers, accessories, finish, overal condition.
With a hammer, ;)
1950s- 60s
50 or so
in good condition how much value?
10-40 USD
20-80 USD or so
No published sn data. 20-60
20-60 USD or so
As much as you want. Whether someone will buy it is another issue. RG handguns typically don't bring more than 15-50 USD. RG didn't make firearms long enough for them to be condiered antique.
10-40 USD