Yes, that is a good deal. The 912 was a nice bicycle, basically the top of the mid-level models, behind the Pro and Team models. I think it's a year or so too early for the well-regarded Splined Triple Butted (STB) tubesets, but nevertheless, it should have a decent set of Miyata-drawn chromoly butted tubes. T-Mar is the man to consult on all things Miyata here.
The 600 EX group will be friction, but should perform pretty well as far as friction goes.