Fresh Air Calibration
The odd AFR reading problem is resolved. I removed the wideband sensor from the header, cleaned it with some carb cleaner, blew it out with compressed air and ran a "fresh air calibration". The sensor was covered with black soot, but not too excessive. I think the fresh air calibration did the trick (I tried recalibrating while it was installed - showed 20.9 but I was still getting whacky readings).
Road Trip
I drove the car from Virginia to Ohio this weekend and had a blast. Back-roaded the entire drive out (winding from VA - MD - WV - into Southern OH up to NW Ohio); ~ 570 miles / 13 hours (with a few sidetracks along the way). Mostly highway on the return trip. Pretty good break in run. Used just under a quart of oil.
I averaged ~ 20mpg; not too bad considering I was running 70-80 mph for a good bit the drive, and stomping on it every time I launched
On my way out, the carbs popped and coughed a bit when rolling through the mountains - LM2 showed I was a bit lean under load (up steep inclines). Roadside adjustment - a little turn of the mixture screws cleared it up. Other than that, the carbs performed great. Although the LM2 shows I'm still rich at cruise, I checked my plugs (NGK BPR 7's) and they look good.
I hid the LM-2 display after I ran for a bit following my roadside adjustment - too distracting / too easy to obsess / too nice of roads and fall colors to ignore...
I'm going to try to get it to the dyno in the next couple weeks - will post an update if I make it in.
Once again, thanks for all the help folks - nearing the end of the season and I'm feeling pretty good where things stand.
Gordo