Just found some information at:
RAF Bulletin No. 3 about a C-130 used for scientific purposes.
But there's also a couple of probably useful images:
There's also a complete table of specifications in that site.
Great reading can be found here:
http://tig.ludost.net/plane_c130.html
Nice images are at the bottom of that page, and here they are:
I hope these are useful for your project
Edit:
A cross section of the fuselage, probably not at scale, but with measurements:
from:
http://www.airliners.net/aviation-fo...ad.main/96080/