You should be able to get a full size pdf file for various iterations of P-basses online, in some cases the dimensions are on the pdf files. I don't know off the top of my head...when I built a p-bass I just traced the pickguard. As for quilted eucalyptus, I have no idea. Most builders stick with the tried and true body and neck woods, and throw the exotic stuff into bookmatched top/headstock laminates. There are a variety of websites that will give hardness and strength measurements of wood species, and if this particular wood passes muster compared to traditional neck woods, give it a go!
Now keep in mind this is just for structural purposes. Notice I did NOT get into tap tone and all of that. You're really opening pandora's box if you start asking those kind of questions.
Modulus Mob #31
Eden Electronics Club #9