Well, the 'finished ' GSM-1 wasn't finished.
That bodged bridge and extra saddle slots really bugged me. Also, I must have messed up the last fret level as even with a high action the treble strings were catching on the first three frets, and when I re-levelled, some of the upper frets were really low as well. I now have a better fret profile file which is easier and quicker to use and I'm getting much more consistent results this year.
This was the original bridge bodge due to the holes being 4mm too close together:
https://imagizer.imageshack.com/v2/8...924/I6FJK2.jpg
I'd found some offset 8mm to 4mm post converters by Kluson, designed for an old Japanese bridge some years back, When they finally came in stock again< i ordered some, along with a Kluson ABR-1 style bridge which has 4mm holes, as it was the only one I could find with un-notched saddles, as I wanted to set the string spacing/positioning myself.
So after I re-levelled the frets again (successfully this time), off came the old saddle and posts and in went the offset converters:
https://imagizer.imageshack.com/v2/8...924/HMH6ne.jpg
I positioned the inserts with the 4mm posts as far away from each other I could get, checked the bridge fitted (it did), then fixed the threaded inserts in place with a drop of thin CA.
I re-used the original strings to set the string positions on the saddles. I first set the two E strings in their correct positions, then used my string spacing ruler to set out the positions of the remaining strings. Then came the classic Gibson method of hitting the strings into the saddles with a small hammer to create the notches. As they are steel strings on brass saddles, they do leave noticeable indents when hit.
It was then a case of throwing those strings away and fitting a new set:
https://imagizer.imageshack.com/v2/8...922/c1mzO5.jpg
The 4mm adapter posts were a lot longer than necessary, poking out of the bridge by approx 3mm. I cut them down before I fitted them in place and set up the action, so they are a bit shorter than they could be, but the bridge is held in place just fine and they will never threaten to stick in the palm of your hand.
The original ABR-1 style Tune-O-Matic bridged didn't use insert bushings, just a single 4mm (or possibly an Imperial equivalent) threaded post which screwed directly into the top of the guitar, so if the bridge sat quite low, you'd have to adjust the length to suit. Whilst I could have screwed the 8mm part further into the bushings, I wanted the transition to sit roughly level with the bushing, not down in the hole, so the 4mm section had to be shortened.
The fret level did all I wanted it to and the action is now really nice and low all along the neck.
Not 100% convinced about the pickups, so may swap those out again for my favourite Iron Gear Blues Engines.