Speaking of JoHan's with incorrect interiors... The USA Oldies series contains many incorrect interiors that were correct when the kits were first released as annuals in the 60's. By the timethat USA Oldies were released a lot of tooling was lost/damaged/worn out. I have a '62 Plymouth annual with correct interior and two USA Oldies versions with incorrect interiors. In fact, one of them came with a '63 Dodge dashboard and the other had a '63 Plymouth dash! The rest of the interior is wrong too but I'm not sure of the source. They used whatever they could still produce. The '62 Chrysler USA Oldie has a similar problem but Modelhaus has the solution.
On the '64 Plymouth, JoHan may have upgraded the Fury interior to Sport Fury specs but I'll never figure out why Lindberg put the Sport Fury buckets in their Belvedere kit! Seems like every model company has some skeletons in their closets.
There also weren't as many options available back then. Forget about the "technology package" or the "comfort and convenience group"! I remember seeing cars advertised as "Fully Loaded! Radio, Heater and Whitewall Tires!".
I'll inject a question into this. AMT created a "new tool" Ala Kart that was not well received but the original Ala Kart was one of the most popular kits of all time. Do you think that there would be demand for a re-issue of the original if they get all the tooling back together again?
The model building basics are the best low cost detailing tips. It's surprising how many models you see that are otherwise well built but there are visible seams where parts were glued together and visible mold lines. The mold line on the radiator header and across the radiator cap bothers me the most. It's visible front and center if the hood is open. Filling seams and sanding off the mold parting lines makes all the difference.
Another good tip is to take the shine off of the tires. Especially true of hot rods or race cars that are open wheeled. The tread can be sanded with a fine grit. If the rest of the tire needs to be de-glossed, it can be coated with a clear flat (or semi-gloss) acrylic or just scrubbed with a cleansing powder like Comet.
It's important to just pay attention to the overall appearance of a model to get rid of the "toy" look.