If your Colt Python has been fired very little, it's worth at least $500 and could be worth twice that, depending on various factors. Without seeing the gun it's difficult to tell.
Others could tell you how old the gun is from the serial number. Though I didn't think Colt used a "K" prefix on the Pythons.
The "ctg" is probably marked on the barrel as "357 Magnum Ctg." or something similar. CTG is an abbreviation for "cartridge". The Python will shoot either .357 Magnum cartridges or .38 Special cartridges interchangably.
If you have the original Colt box, owners manual, cleaning kit and other papers with the box, your gun will be worth more. After handling, put a few drops of oil on a soft cloth and wipe down the surfaces of your Python to remove the fingerprints and skin oils which could help start corrosion.
BillCA in CA (Unfortunately)