As far as kit manufacturers go today, every subject created must have the potential to easily be transformed into a number of other kits.
Look what Moebius did with the '53 Hudson.
It went from a stock Hudson to a racing version, to a '52, to a convertible & then to a '54.
"You have to maximize your tooling in order to stay in business.
What would you get from a '74 Chevy 4 door?
A stock version & a police car, that's about it."
What can you do with a 78 Monte Carlo? Stock?? Lowrider????...In fact Trumpeter never did anything with it except stock. They still tooled a brand new kit from it.
But as you pointed out with the Hudson. They made a stock car version of it, chopped the roof off, made a convertible, changed the grill, made the next year up.
So why not with a car like a 74 chevy 4 door, have a police version, taxi, even a lowrider (4 doors are used aren't they?) and then utilise the mold, change the roof line (Like revel did with the 57 ford to make the wagon) and have a 2 door Impala and convertible?