So after a long time of being discouraged because of this diagnose, I continued working on the kit. Thankfully I was checking other EX-Threads as well and apparently many had the problem of an angular neck heel front. So I had a closer look at mine and sanded carefully to even that out. As it turns out, the neck sits now in a way that the strings are correctly aligned
Further, I experimented with maple veneer to get the right shim height. It took a bit, because somehow the neck was rocking up and down a bit in the neck pocket, but I figured that i just had to put more veneer closer to the bridge to angle the neck even more and that worked out. If put into the pocket, the neck now sits tight, the strings have a reasonable distance and the bridge posts don't have to be all the way down.
Now that that was taken care of I sanded everything, watered, sanded again and started applying the birchwood sealer and filler to prepare for the tru oil application. I diluted the Sealer with naptha to make it easier to apply. Unfortunately, I have gotten a few runs which I will have to sand out again. You can see though, that there's already a nice shine to the body.
I used spray can lacquer for the fretbord and gave it several coats.
While that was happening/drying, I used the maple veneer to build new covers for the Truss Rod and the electrics to replace the plastic parts.
I also bought a new graphtech TUSQ nut that I will put in once the neck is glued in, in order to then sand it to the right height.
I've been thinking of putting my signature or a logo on the headplate of the guitar. Since I didn't come up with a nice logo so far I will probably go with the signature. Do you have any recommendations what could work well with tru oil? In one of the pics you can see a discarded shim with some markers I tried with the tru oil and how they bleed
out.