The one I use is also one of the 1 1/4 bar setups, and now that you mention it I think Dad did say once that the mike came from a Kwick-Way setup. Given that he had one of those back then too, I'd just about guarantee you that's where it came from. Too, your right, with it you've got to be sitting in eactly the same spot every time to get an accurate measurement.
What style drive head does yours have? This one has the gearbox that's driven by a Milwalkee drill head. If this is what you've got, and you ever have trouble with it, (and haven't figured it out already)you can take a standard head and have the nose of the housing machined to fit the gearbox just like the factory one. Dad did that years ago so we'd have a spare motor to keep in the box after getting halfway through a job, in the middle of nowhere, and it crapping out on him.
Talking about press fit bushings, have you ever used any of the Connex spring bushings? The RR's track machinery repair shop turned us on to them years ago when we were doing alot of portable boring work for them. What they always had us do was bore the hole back overized and install a Connex to bring it back to the size they wanted. With them being a spring, you can bore the hole a little larger, or smaller to get the pin clearance you want. Because of that they are a bit forgiving as far as the fit goes when a few thousands over or under don't make alot of difference. Over the years I've used them with good luck