Then only way to know for sure is to get it lettered.
Yes, they called it their "Youth Model" a.k.a. Boy's Rifle.
Make, model, and condition. We need all 3 to estimate a value. Sorry.
K0204fcu is a 1985 5.0 305 cubic inch Chevrolet small block with a 4 barrel carb
Yes
No
Yes
Yes
Did marlin make a goose gun with a thirty nine inch barrel
If your 20 inch barrel has screw in chokes then get a full or extra full turkey choke tube and you'll be fine. Just make sure to pattern the shot with your particular barrel and choke combination. Also make sure you know where the point of impact will be with your sights. The 24 inch barrel would be fine also as long as it's properly choked etc.
Yes
Probably.