Back in the eighties I picked up one of these kits and put the 54cal barrel on it,could punch holes in playing cards offhand at 50yds no problem, got my first muzzle dear with it too. IIRC I paid just under $200 for the kit then. The stock on yours does not look like factory finish and the bluing on the metal does not look factory either, whether it is a kit or refinished is impossible to tell.The early guns were 1" across the flats and later 15/16"
If the barrels are clean,and the triggers are good, as a set, it could be worth $350.