I've finally reached the point where I can say that I will no longer delve into the guts of this beast.
Honestly I've no idea of the amount of hours I've put into it, but it's now very nice to play and sounds great!
Currently it's setup with 12-56 gauge round wound strings, has a Wilkinson Roller bridge, Bigsby B7 with Vibramate and a pair of matched humbuckers from a Gretsch 5120.
The original and replacement PAF style pickups never sounded much good to my ear, and the P-Rails did not really suit. The Gretsch pickups have turned out to make the guitar sound rich and gutsy. Excellent clean tones and can really drive a valve preamp.
I modded the Bigsby a little as the arm did not come far enough over the strings for my playing style. I filed the aluminium nub down a to get the end of the bar over the 3rd string. This way I don't have to reach across with my stubby fingers to play the way I want to.
As with many things that have passed across my guitar rack, this one was recently sold, in favour of another instrument that is on it's way to me in the post. Somehow it became apparent that I might have too many electric guitars and not enough tonal variety.
Hopefully the new owner appreciates the work that was put into it.