If you're going to the trouble of that, why not an original body? You can get ideas from places like this:
http://www.destroyallguitars.com/newarrivals-guitars
And there are a couple of sites that index schematics and drawings:
http://shortscale.org/forum/viewtopic.php?t=38813
http://www.gitarrebassbau.de/viewtopic.php?f=10&t=6&start=0
Sizing shapes up to scale really isn't hard, I'd bet your grandfather knows that stuff. If you can get a shape onto graph paper of any size - you own it, from there. Just make bigger squares and transfer the lines.