Hi Daryl
Just noticed this thread, i remember these coaches well as i used to actually change trains at newcastle on journeys from Edinburgh to York to get some Class 47 haulage.
The lower bodyside colour on the Trans-Pennine liveried coaches was the same as the Intercity livery on the HSTs, if any of these coaches later in their life carried Regional Railways (RR) livery it would have been after a complete repaint. RR was a totally different livery not just a simple case or re-branding it had a different depth and height to light blue band and the lower panels were alot lighter and silvery, there were quite a few rakes of Mk2s used by scotrail from about 1992/3 onwards in this colour scheme that i have pictures of i will just need to find out which external drive they are on so i can post them.
Should be a nice simple repaint job, good luck with this project i look forward to seeing the finished article. I actually thought about doing a rake a while ago but didnt have the courage to chop up some bachy Mk2s to get the Mk2c coaches so i flogged them on eBin instead.
Kind regards
Bry