Welcome Jesper!
Your dead zone seems to indicate that your frets might be worn down, which is common with vintage basses, especially if they were played for many years with roundwound strings -- as opposed to flatwound, which are smooth like upright strings and really don't grind (or wear) down the frets. That results in taller frets, usually closer to the body since these higher notes are typically played less frequently. If this is the case, a luthier can usually level the frets for you by filing the frets until they are all the same height. Sometimes the frets are extremely worn, in which case they may all need to replaced with new frets.
Another possibility is that some of the frets between 12th and 18th frets have sprouted (or lifted out of the groove they are set in), which usually happens when a fretboard dries out. In this scenario, the frets would need to be tapped back into place with a small hammer, but VERY carefully. The frets are made of relatively soft metal and can be damaged if the person doing the work is not experienced.
Finally, it is far less likely but still possible that your fretboard has a hump (or ski-slope), which is a craftsmanship issue that I don't think I've ever heard reported about USA Guild instruments. Essentially the hump or ski-slope issue occurs when the fretboard is not completely planed (or flat) from the nut to the body. In this case all frets would need to be removed and the fretboard would have to be properly planed. In extreme scenarios the fretboard may have to be replaced completely.
Before any of these things though, I would try to tighten the truss rod first. It is possible that your neck is bowed forward too much under tension of the strings and it might just need to be flattened slightly, which would allow you to raise the bridge without the string action getting too high on the fretboard. The bow is often referred to as relief. Some relief is necessary to avoid fret-buzz when playing in positions closer to the headstock. Proper technique for tightening the truss rod is to loosen the strings first and then turn the truss rod clockwise, but only 1/8 turn to avoid the wood cracking. Then let allow time for the would to adjust gradually. Repeat if necessary.
I could be wrong, but I think what you mean when you say "saddle" is actually the bridge. The saddle is a small part of the bridge and there is one for each string. The typical bridge that was installed on these basses in the factory was called a Mueller bridge, as the one shown in the photo below.
I did my best to name all of the parts of the bass and hopefully these photos are helpful to you. I'm sure you already know some of these terms, but I wanted to be as detailed as possible. There are sometimes multiple names for different parts, so I tried to list any variations I could think of. The photo of the "Wiring Harness" that I labeled is not from a B302 bass but from another Guild guitar from the same time period. The last photo IS of a B302 Wiring Harness, but since it was previously labeled by somebody else, I did not want to clutter it up with more names.
Front View
Back of Neck
Mueller Bridge
Tuner
Wiring Harness (Not from a B302 but still a Guild from the same time period)
Wiring Harness, as mounted on pickguard. Copper foil tape is for "shielding"
(This photo was labeled by somebody else, but I thought it could also be helpful)