Looks great. You are often too critical of yourself. The ONLY thing that jumps out at me is the angle of the steering wheel. In the '50's the wheel was almost vertical. Was this built into the model? Is it something that can be changed?
Outstanding, as usual !! I do believe the early GM windshield washer systems worked by vacuum. The one in my '56 Olds, I believe, was Tee'd off of the dual action fuel pump on the line that went to the wiper motor.
As to the torque-tube chassis, JoHan wasn't always well known for their accuracy. Most, if not all, of their two door hardtop kits and promos used the interior bucket from a convertible. I guess it was easier, and cheaper, to use for both models even if it was wrong for the hardtops. I imagine the same can be said for the chassis. They probably did a '66 Marlin, Classic or Ambassador and just continued to use it for The Machine.
Sometimes you can pick up a promo model off of eBay at a reasonable price. That's what I did for the model Ramfins built for me. On all the Rambler American kits and promo models I've seen from Jo-Han they based them all on the convertible which makes the rear seat area on the hardtops WRONG.
Excuse me, but I was not being smug about it. My info source was the 3rd Edition of the Standard Catalog of American Cars 1946-1975 and 50 years of driving. That being said I will now admit I was WRONG. The Del Ray seems to have been a trim package within the 210 series. It provided carpeting and all vinyl upholstery in place of the rubber floor mats and vinyl/cloth seats.