Sounds like an ideal project gun. I ran across a Mod 19-4 a few years ago in a similar situation. Literally new gun, but left in a soft zip case after getting wet in a house fire (didn't get near the fire). It had pretty sever rust and finish damage, but the pitting wasn't too deep. Tore it down and the inside was fine, so sent it to Metaloy in Berryville Arkansas with instructions to leave the entire top rib black. I think it turned out pretty decent.
The price I paid and the cost of the re-finish total less than what it would have cost to buy a like new 19-4.