Kimtab Tabloc wheel question?

Hey guys, haven't been on here for a while. I recently decided to part with a pair of Kimtab wheels I've had hanging in the garage for a while. I got them with old tires mounted and left them like that. Well I decided to clean them up to sell and took off the tires. The inside, especially on the front, has LOTS of pitting, and almost looks like globs of magnesium. Were these machined smooth when new? The outside of the wheel is great shape, very little pitting. Also, there was lots of white powder inside, almost like plaster? These had tubes, but knowing how leaky magnesium wheels can be might of someone tried to seal them up with something? I just took a wire wheel to it to clean them up some. Anyone know what year these were made? The only thing I found was a "585" on the 18" and 595 on the 19". I figure early 70's only because I heard these were the inspiration for the bmx motomags of that period. Any idea on what they are worth in this shape? I know I've seen them as high as $1600 a pair.