It was a no go. The place I was in contact with said they didn't know why their site showed such a large inventory of G749 wheel cylinders and other G749 parts. In fact, they pointed me in the direction of who did buy up all of the G749 NOS parts. Which were places like Memphis, Niagara and Boyce.
White Owl equipment has wheel cylinders though, at $48 a piece. I just contacted them about some. Not sure about condition but at $48 a piece they'd better be like new or NOS. Luckily the truck I bought has already had 8 wheel cylinders rebuilt, master cylinder rebuilt and the bearings pulled and repacked. Saves me lots of work!