I've made a little change in direction because of a deal I couldn't turn down. A friend at work heard I was looking for an old bike and offered his 1990 Giant Rincon MTB for $100. It's a low end bike with CroMo main tubes but Hi-Ten stays and fork and is pretty heavy, but it is a very solid bike with eyelets front and double rear. It is a 21 inch bike and I normally ride a 19 inch MTB. I think the larger size makes it much more suitable for converting to a drop bar dirt road tourer. What closed the deal was that the bike is basically unused. It has maybe 100 miles on it and has been hanging in a garage for 15 years. Other than a layer of dust it is pristine. Not a scratch or rust spot that I can see and everything works like a new bike. At the very least I can use this frame as a test bed and later move components to a classier frame. Or I just may decide that this works fine.
So, what are some good 26" tires for low rolling resistance on roads, but some ability to get traction in dirt? Club Roost Cross Terra, Hutchinson Acrobat, Continental Town & Country, Kenda Cross, Schwalbe Marathon and Kenda Krisp are a few I've seen.

I had hoped to use a dirt drop handlebar, but they don't seem to be made anymore. I might try a Nitto Moustache bar. Another possibility is to take the Nitto Randonnuer bars from my road bike. I've been looking for an excuse to try Nitto Noodle bars on my RB-1.