Thanks, see if these are clear enough. The patent dates are hard to read.We would like to help you but you need to post pictures. Please see the link below. Thanks.
The patent dates are just that, the date the patent was approved. More often than not they have nothing to do with the year the firearm was manufactured. I'd have to look to be certain but as an example I believe the '73 Colt SAA patent dates are from 1872 and maybe one from 1871. Those dates will be on a Colt SAA made in 1940. I would suspect yours and OG's dates for the rifle are correct.
Marlin serial numbers...I admit I am dumber than a box of rocks about them.
Unfortunately the hammer spring was the victim of a shade-tree gunsmith. Best I can tell when the "repair" was made they tried to beat the stock back on and destroyed it. I think there is enough of it left for the duplicator to map. I have a bunch of 200 year old black walnut that should dress it up nicely. I wouldn't put a ton of effort into it, but it is going to be my son's (he's 2) first gun, so I'll put more effort into it than I should. I'm going to leave it as a .22 short, just so in the future he doesn't try to feed it high velocity ammo and get himself in a bind. I'll have a grand total of $40 in it by the time I get all the parts in. It's hard to beat a free gun even if you have to tear it down and start over!Purely my unsolicited opinion; That one looks as if some make-up and lipstick wouldn't hurt much. Personally I wouldn't try to make it look new but that's me. New wood made to look old, make everything fit as it should and just clean up the outside of the metal a bit is about as far as I'd go.
The internals look amazingly good but I ain't sure what's goin' on with that hammer spring. It looks broken, is it?