To follow up, I purchased the Space: 1999 set (10 discs total, seasons 1 and 2) on blu-ray. The box shows a symbol which would indicate Region B. When I got the set, I thought, why not just pop the thing into the BDP-83 and see what happens? Can't hurt, right? So I put the disc in, and voila, plays like a champ! I tried another disc in my Panasonic DMP-BDT 215 - and it plays it too! So apparently this set isn't really region-locked. Which is great, because the picture quality is quite good and it's a fun nostalgia trip going back and seeing this series again.
BTW, on all the discs I've looked at, the shows are 1080p and the extras are only a series of still pictures. So if there is PAL content I'm not seeing it. Really happy that it turned out this way!