The original pads were probably Conn-foil pads with metal foil under the leather, or more likely, Conn reso-pads with small flat resonators riveted to the pads and metal rings (or more accurately, flanges) around the outside edges of the pads, also inside the leather.
Conn reso-pads are still available, but somehow the rings (flanges) inside the edges seem to have grown in diameter. The new Reso-pads fit so tightly in the old Conn pad cups that they are difficult to install. Of course, the original Reso-pads were intended to compete with the Buescher "snap-on" pads which were touted as easily replaced by the saxophone owner... I have seen many old Conns with reso-pads installed without glue, so maybe the first Reso-pads were tight fitters, too.
The original Reso-pads were introduced at a time when Buescher had great success with their snap-on pads. The "snaps" acted like resonators and made the old Bueschers a bit louder, so Conn introduced Reso-pads with small flat resonators about the same diameter as the Buescher snaps.
This was in the early 1920s, so check your serial number to see when your horn was made. Reso-pads were used after about 1920-22.
Of course, things have changed in 80 years, and there is nothing wrong with repadding your Conn with modern pads with larger resonators. you may like the sound even better with larger resonators. Your repairman will probably like you better too, because the modern large resonator pads are easier to fit than Reso-pads. Thinner pads (.160" thick) will probably be better unless the keys are bent to fit thicker pads.
My Myspace page:
http://www.myspace.com/saxpsychosis