Can't help too much with string specs. The bow is probably from about 1980 or so. You might call customer service at Martin and ask for one of the tech reps who might have that info. Otherwise maybe one of the many custom string makers would have that info (Winner's Choice, Vapor Trail, or others).
I Googled it and came up with nothing for tech info. However, there are a bunch of ads listing them for sale so one of those fellows might have the info.
Sorry I couldn't help more.
If You're Not Living on the Edge You're Taking Up Too Much Space
Martin/Rytera Staff Shooter
PSAA Life member, UBP Life member
PADI AOW Diver