Just a small leap here, but when you mention the NADA book your clerk was possibly looking to place a value on the car for sales tax and yearly VLF fees as they unlike California do not care what you paid for the vehicle and pick a value to charge you on. When the clerk could not find a Sunbeam in the mfg. list she hit the wall and stopped there. Maybe some comparable sales and a bill of sale and an offer to let the manager inspect the car would help. I had some exp. as the MRS is from VA Beach and had some fun in VA DMV when there. Also I know my father in laws MGTD was super cheap as an antique auto. We suckers in Calif pay 80 bucks for the minimum per year.
There is another option which may help but I have not done it on a car, but motorcycles has worked for friends. Vermont DMV does not title vehicles over 15 years old . The idea is you get a plate a registration which will be honored by your home state. The have a 800 number and the chatty convicts they employ love to help. It is my understanding that it may work for a car as it is over 15 years old. Call them and ask they are very helpful. They do run the vin thru NCIS and theft databases. In Calif. all that is gained is a cumbersome CHP DMV inspection that sometimes takes several weeks for a appointment, but guys do it anyway Here is a neat link as well
https://www.nicb.org/theft_and_fraud_awareness/vincheck
Way back in the early 80’s VA DMV offered tourist plates for a car 3.0 CSI coupe I brought from Italy I got a title with no inspection and brought it to California they were called tourist plates available thru AAA of VA. still available I am not sure good luck