help ID carb

I double checked the number; it is 4200S. I cleaned the chalk up a little better after taking the picture.

A web search on "Carter AFB 4200S" showed a couple links pointing towards a '65 high-performance 383/413/426.
http://www.carburetion.com/Kits/dodge.htm
I remember the car had a 273 emblem. It sure looked to be a LA series motor, my '74 Roadrunner was a smallblock). That was why I grabbed it; figuring a carb from a 273 would not be overly large for my 225 v6.