Interesting about the stamps. And those 85 NOS carbs you have are a niiice find.
here is a closer pic of the stamp on Toby's carb. Clearly restamped, a 5 over a 4 as you mention, plus the "JCY" designation. I do believe this was done by the factory.
The recoloring is Eastwood Carb renew. It is the best product out there for a spray-on coating. It holds up well to Gasoline so long as you let it dry before handling it. It doesnt "melt" like most other spray-on coatings out there, and the color is right. Cleaning and detailing of the carb is best accomplished with dishsoap and water.
Plating and Chromating offers the best protection and appearance for the Qjets, but the EPA regulations can make it difficult for a small operation to implement it. I plan on plating in the future, but do not offer it at this time.
EDIT MARCH 2014 - I wanted to update this because we are now offering plating and chromating services on our quadrajet rebuilds! See the finishes on our facebook page! https://www.facebook.com/pages/Everyday ... 8290844413
For the hobbyist (exempt from the EPA regs), I recommend the Caswell CopyCAD plating kits. Plate the parts then dip them in the chromate solution for a near-original finish. I have used the kit on a carb or two of my own with good results.
EDIT: note the Julian Date on Tobys carb 157th day of 1984 so definitely a 1984
H/O carb prior to the OEM restamp