I was asked to rebuild a PRMRP 56 for someone ok i thought what a night mare I ended up just using the bogies, motors and body wrap and rebuilding the rest with a lot of help from Mr Parkin for a few parts and 3D printed cabs and new etched parts.
They were good kits in the day and they are a good starting point now but you have to think out the box with how to improve them to modern standards.
Ray you have done a lot and some JLTRT cabs will solve about 90% of your problems, they transformed this DJH 40