i took a quick look at rockauto.com and they list only drum brakes. did a general search on google and when i asked about disc brakes conversion kits came up. you might be able to get a local autoparts place to try and match them up. look in a repair manual that will also help. keep searching!
Front discs were an option on the Polara and Monaco in 1967. If you have the original wheel covers, they actually say "disc brakes" on them! You probably have the four-caliper Budd discs, and if you do, you might as well own a Rolls-Royce, because they are extremely hard to find and very expensive. Pull a caliper. If it 's the four, they are the spendy Budds. If not, someone probably put later "C"-body discs on it, and you are in good shape there.
I'm with patrick80. If you have the 4 piston caliper, I would sell them to make the money to buy a '68 on up set up. The knuckles will bolt right up and parts are cheaper. That is why I bought a chevy wagon. The mopar wagons were bringing serious money.