See related link
yes
Marlin model 80
It is possible
22 Long Rifle
.22 short, .22 long and .22 long rifle.
Best to let a gunsmith do this.
No published history
Try e-gunparts.com or Brownells
15 long rifle--will only operate auto with lr ammo
Your serial number indicates that your Marlin mod 60 rifle was made in the year 1978.
I have looked for myself and I now believe that it was made by Ruger.