Dan-
Regarding material, vast majority of Carlsbad frames were Reynolds. If you want to measure, Columbus fork blades will be 19.5mm +/- just below the blade reinforcement, Reynolds will be 16.5mm +/- thick across.
Very few Carlsbad frames had a tubing transfer, perhaps only a handful.
As you have also found out, Masi measures to the tip top of the seat lug to get the frame size. So to some, the bikes run small.
Clinchers are a change out, Original freewheel would have been an Everest, 14-22 or 14-24.
John Jorgensen
Torrance Ca USA