You can check the yr it was built in the FAQ's. It is a cast iron frame. They had no other designation before 1987. Personally I would not put a centerfire bbl on it but some have used the low pressure bbls. They have very fat firing pins that can cause problems with the centerfire bbl's. Shotgun bbl's should be ok pressure wise but the fit of newer bbl's is iffy and will most likley need to be shimed. Values are mostly whatever you can get for it or how bad someone wants one when you go to sell it. Anywhere from $60 - maybe $150. There are several past posts on the forum and in the classifieds. Kurt