That's a beautiful set Jim, the family is indeed fortunate to have your assistance!
You will probably receive a great variety of estimates so here is my 'currently uninformed' opinion:
It is sad that no one in the family wants this as it should have the most value to them because of the personal and historical factor. Otherwise it is 'just another very nice antique toy' to the general public. I would imagine that fact that it has been restored could in some buyer's eyes actually diminish the value although it is certainly a beautiful job from your excellent photos!
The market is almost flooded with postwar items and in general, the market (us) most interested is shrinking because we are slowly passing away while younger people have little to no appreciation for these pieces. We have to admit that Nostalgia is likely the driving force in postwar trains that the younger people don't have for logical reasons.
Add to these factors the abundance of similar NYC locomotives from over the years produced by Lionel, Williams, MTH, and even Marx and American Flyer, there are almost too many choices for an interested buyer.
My guess as to a $$$ value is just that - a guess. $300? maybe a little more? If they were mine, I'd surely hang onto them!