Eliminating the yellow vintage cloth to run the 4PDT sure does make things a lot simpler. Thanks for pointing that out - it's genius!
I'll take your advice on board regarding heat shrinks, avoiding ground loops, and wiring short runs when it comes to hooking things up. I'm feeling much more confident with this now - thank you.
I appreciate the photos you sent through - it's given me a lot to think about regarding fitting all this through the f-hole.
I'll post some photos when I start work on this over the weekend.
You've been really helpful with all this - thank you. Simon has been incredibly helpful too.