Record Brake Pads and or refills

I have used Campy Record (with a few Chorus bits here and there) since
pre-Ergo-Power / STI era. I installed Ergo levers in late 1993 for
the 1994 season. In that time till today, I updated bikes to match new
bikes that had / have complete Record sets. I think the bike I am
working on has primarily 2002 Record, maybe 2003 model year. The
calipers are the “D” model (long before the 2007 “Skeleton” changes)..
I can’t figure out how to replace the pads or refill them. The problem
I find is that the other pads I have around are not shaped to fit in
the orbital recess. For flat pads, the profile that effects them
causes the pads to move down below the ideal location for gripping the
rim’s brake surfaces. Is there any way to install pads properly
through a readily available alternative for either the entire pad, or
to refill those that I have. Also, there are no set screws and it
looks like the one end being open means I need to push them out
against the direction that the rim surface pushes them.

Any ideas or insights? I need to use these calipers ASAP, or I will
need to install a caliper lying around and I have not used any other
calipers since moving to the Sierra foothills where brake performance
is critical from the moment I leave the driveway.