I have seen downloadable tables for the Radio Shack meter but that is a bit of a Holy Grail device here in Canada considering we haven't had a Radio Shack in many years since they pulled out and got replaced by "The Source".
Murph, if you are interested, you can get the Radio Shack SPL meter through Sonicboomaudio.
I will have to look around to see where I read the avia disc is out of whack.