I had a 91 8500 which I loved to bits, lasted about 10 years before the chainstay cracked from too much chain suck!
Didn't realise Trek did a 8700 Pro...maybe this is a US model...think in the UK the 8700 came with Suntour XC Expert...the model up from there the 8900 came with XT, some trick components and a set of original rock shox...have a review of the 8700 somewhere if you're interested, and a 1991 Trek catalogue to boot
And to answer a few questions....JustKev none of its original except fork and headset. My plans are to build a XTR group/Syncros build. I am trying to source out a Trek Fork (DDS3 or Trek Mogul).
Check out my other thread....I have some other builds going on as well but this one is my baby (well excluding my actual 6 month old baby girl!).