Nice addition to the collection! Glad an collector got them!
I do own that sign and I was looking at those apparel items on Lincoln Radiator was my hometown dealer in Lincoln, IL. He did have some great stories about being on the Dealer Council, and he participated in the Indy Speedway events. He opened his dealership in 1959, and sold out 50 years later in 2008. I bought the sign on the auction. I have no doubt that's where the apparel came from as well. Being a 50 year dealer who also collected many things, the auction was a figurative goldmine of vintage stuff and the auction drew a lot of collectors from the east.
That sign hung in the barn the last 12 years and has actually only in the last month come out of the barn to be worked on to hang in my shop. Unfortunately the other side has better color but took more damage. I have the pieces for the large hole, just working on gently cleaning and repairing.
replacing the old fluorescents with LED strips
I also made a mini replica on my 3d printer.