Jay, I don't know what to tell you. I didn't have any clue how to calibrate it and nobody else is answering, so I went looking. I checked a factory 1979 service manual, Chiltons, Google search, Jeep Bibles, and called a couple of buddies who run them. I couldn't find a real answer. On the IFSJA board there is a new post about this, the best answer he has gotten is to find a Jeep with Q-trac that came factory with the ratio you now have and rob it's speedo adapter. Nobody I know who runs it has recalibrated theirs. Sorry.
The only reason the Q-trac is unpopular is because people don't take care of them which usually leads to premature failure. The main thing with that case is to make sure the chain doesn't get too loose. Take the plug out and check the chain tension. Make sure you have the proper additive in it. You may want to look into a part time conversion. There are a couple that offer the conversion with an 18% under or over drive built in that can save you an axle regear.