Years ago, there was a 65 Riv on the LA CL that had coilovers on all 4 corners. I wish I had checked the car out.
I did my vents a 4 or 5 years ago, so my memory is hazy on it. Seems like it was generally easy. Basically, the thick chromed leading edge is the main part, everything else is attached to it. There's a phillips head screw at the peak, buried under the felt channel, and then two large phillips head screws holding the sheet metal part to the main chrome part. The only thing that stuck out to me, was during reassembly, it was easist to push the peak together, put that screw in, and then squeeze it together and put the bottom two large screws in. I must have had the driver's side apart 20 times grinding on the rubber in different places to clearance enough for the window to close all the way.
FWIW, any GM power window motor from about 58 on will bolt on. I installed 58-64 impala motors on mine. I left the lock screw out of the shaft where it meets the motor, because it seems to walk back and forth during rotation. I cobbled together switches and modified my switch panels for them, but haven't ran wiring yet. Also, that vent window shaft is soft metal, and can be twisted to clock the window in relation to the input. I used two crescent wrenches to do it.
Another edit. The weather stripping in the channels is a glue in fabric backed felt. I used 3M yellow glue on it, it seems to be holding well. Used 3M black on the parts around the top, for the foam. You've built cars before, it's probably standard stuff for a GM. My last car was a 67 mustang, it might as well came from a different planet compared to the Riviera.