I just got the decal off ebay. I applied satin nitrocellulose lacquer on the headstock (I masked off the edges and the fingerboard before spraying).
Once I had applied around 6 very thin coats, I left it for 2-3 weeks, and then flatted the finish and then buffed it to a sheen. Leaving the lacquer allows the solvent to evaporate so you get a smooth surface when doing the wet sanding / flatting.
As for the pickups and preamp, I just did that on a whim.
If I was doing it again, I think I'd just do the preamp upgrade and keep the original pickups.
When doing the headstock, I also rolled tge fingerboard edges so the neck now feels really comfortable in the fretting hand.