After years of converting just about every make of Large Scale (North American) freight cars to body mounted Kadee Couplers, and using the Kadee #1 Gauge couplers, as the standard on our railroad. My only comment on the Kadee couplers on those cars, is: The person doing the conversion took the easy way, and did the job VERY poorly.
The pictures also indicate, that for some reason, some of the grab irons have been replaced with wire substitutes, and some of the trucks are not the originals, and are rather crappy. One truck shown, has one pair of metal wheels, and another of plastic.
Proper replacement (Bogies) trucks, for those cars needing them, are available, as are most of the other missing parts.
You may find that the cars perform "OK", but they would be better if properly lubricated with a plastic compatible gear lube, and the trucks on at least one of the cars replaced.
Properly mounted Kadee couplers, would also be advised, if a person cares about making them look prototypical. The general coupler I would use would be the Kadee 1906...or the larger 906. It would involve doing a bit of cutting, but would reap rewards in appearance, and operation, on minimum curves of over 5 foot radius,
The bottom line, of course is; they are now your cars...as long as what you do with them, pleases you...that's all that really counts.
Have fun...
Fr.Fred