Hey I am just reconfiguring my touring set-up AND I ride a Miyata 1000. I believe mine is an 86. That bike can easily handle a lot of weight spread all across the frame. Even though my bike can handle a lot of weight I too am looking to go lighter. I am thinking like you, small front bags and a dry bag on the rear rack. I think might have the best volume weight.
I also am looking into Epicdesign bags
http://www.epicdesignsalaska.com/
Uses no racks, bags on the frame triangle, large rear saddlebag and interesting handle bar bag. They tend to design with the mnt bikers in mind. I emailed them(Eric???) about touring bike bags. He said they had built some frame bags for touring bikes. He recommended some of the saddlebags that would fit a touring bike. Seems interesting but haven't explore totally yet. Let us know how the system works.