Here's the pics of the thrift shop 500 and of the 400 I got off the local CL a few months back.

I went ahead and peeled the yellow plastic/fabric bar tape off of the 500 and found some old Spenco slip-on tubular style sewn on sleeve type stuff (don't know how else to describe it).

And it looks like the previous 500 owner was having some sort of stem slipping issue because there is some gunky remains of some sort of tape or fabric down in the headtube and also stuck to the stem. I'll have to clean that out before I put the adjustable stem into the 500 that came off the 400. The parts swapping begins