Before I spent a $100.00 on anything, let alone a picture of an old model kit, I would want to touch it, feel it, even smell it. Just too many horror stories of the kit not being what was presented in the picture online.
You might want to consider using an automotive self-etching type of primer as a base. Then use the Tamiya primer for sanding and a good smooth surface for the color coats.
Seems like anything having to do with our health, and Dentistry is no different, just cost a lot of money. I had a crown breakup just eating some breakfast sausage one morning and that was almost $500.00. The crown was less than 10 years old. I don't know how long these things are supposed to last, but for the price I was expecting longer than that. I have a crown on one of my front teeth on my lower jaw that has the same crown for many years. It was first done in my teens after a difference of opinion with someone else.
Beautiful looking paint and trim. Like the wheels and tires. The real '60 Plymouths weren't the most attractive looking cars but your version of it looks great.
Based on one of my old shop manuals, Motor Auto Repair dated 1967, the 413 in the Imperial was offered with two different horsepower ratings. They list one at 340 and the other at 360 hp. Since they both list having the same single 4 bbl carb., compression ratio the only differences maybe the cam timing and or the size of the carb. Any good-looking engine in the correct scale and representing a 383 thru a 426 wedge should work out.
The Charger side panels look a little more finished than without. On the other hand, with the seat alone and the rear inner fenders exposed that could represent a vehicle with rear wheel tubs. Just depends on the nature of the build. That AMT '60 Sunliner is a great kit.
Remember a "Morning Drive Radio Personality" that got fired after repeating a common joke of the time about a Pinto that caught fire when one of the Firestone 500 tires blew and the fuel tank exploded. Seems one of the radio stations main advertisers at that time of day was the local Ford dealer. Guess he didn't have a sense of humor.