Nice stuff you found at that show, Ray! I only wish we had such shows here in Europe, too. (Yes, we also have shows, but you hardly ever find American rolling stock here in Europa.
)
I remember that I bought a pair of Buckeye six-wheel trucks from WALTHERS back in the '70s - sold under that label. The basic construction seems identical to the type of construction of your trucks. Of course the cast truck frames are a little different in shape, since they represent ALCOs. The frames were white metal castings, and the trucks had brass wheels like yours. Perhaps this info could help you a little bit???
Concerning electric motors: When you get such an old kit, do you use the original motor? (Like the open frame motor in the fourth pic.) Or do you replace them with new ones? Could it be that the magnets lose their strength after 20-30 years?
The reason why I ask is, that I also have a few old Roundhouse kits. When I tried to test-run such a motor it only ran very slow. Or could it be plain dirt in the bearings which slows the motor down? (I admit, I didn't clean the motor before connecting it to the power pack. Just took it out of the kit box where it had lain for 20+ years...
ops: )
Ron