Good luck -- I'd be interested to see what you get. BTW, I think D8 is the size designator (like B2, which was Agfa's 120 film); the frame size you describe is that of 116 and 616 (same film, different spools -- the same trick as 620 vs. 120, only 30 years earlier). The film type would probably end in "pan" or "chrome" (Agfa made both Isopan and Isochrome at various times, both conventional B&W films), though it's highly likely Agfa had other commercial names for films over the hundred years or so they sold film. You might be able to find that name at the head end of the backing, or between framing numbers, once you've loaded the film into a reel. Having that might allow you to find a reference for the actual, original recommended time.
Of course, if the film was made after about 1934 and before about 1970, it's a very likely bet it'll want 7 minutes in D-76 stock solution, with agitation every 30 seconds -- that was the B&W standard for drug store processing (often really done in the back of the drug store!) until C-41 color films gained the upper hand with the family snapshooter and B&W films could diversify into individualized development regimes. Even earlier B&W roll films are likely to work with that development, though it wasn't until the D-76 era that commercial development really became common; most photographers prior to the 1930s developed their own film, often making their own prints as well (frequently on POP, due to ease of handling).
