I'm surprised the seem to be permanently coupled. I agree that there is probably a screw connection under the weights. I would redo with a drawbar on one unit and a pin on the other so you can lift them apart.
As for wiring, probably the way they are is probably most reliable. The wiper setup looks very well done, if not factory. I have never seen the underside of these so I can't say what was done originally. The prototypes were not run as individual units as far as I know. Everything I have read, says they were run in pairs both by PRR and LI. PRR sold or leased some to LI. If you used a plug connection between them and left them wired this way, they would have very reliable pickkups. Remember more pickups are better than less for overcoming any dirty track. I have an 0-4-0 switcher and I put extra pickups on the insulated tender wheels.
It is somewhat complicated to change the rods so the insulated set up may be the way they were built. You might look for evidence of a plug connection between the units that has been removed.
The kelly green is not very prototypical. The prototypes were painted the PRR "Dark Green Locomotive Enamel" which we call Brunswick green. This is an almost black looking color. You can readily see the green tint when placed next to something that is black. So a much darker green would make more sense Scalecoat made a PRR Brunswick Green that you could even darken with black if desired. The lettering on all passenger stuff in that era should be gold leaf or bronze, not DULUX yellow. They probably got the yellow eventually. Also I have seen photos of models with the 5 gold stripe scheme, but I don't think I have seen prototype photos of that scheme. Not sure on that. The red window frames are accuragte. By the wya there is a prototype at the museum in Strasburg PA.
