Hi Eddie,
heres the skinny on the rigging of the 5.0. We have 7 in our fleet here in Columbia SC, and 2 of them we got new sq top mains from Calvert, both a little different, but both boomless.
The simple rigging involves the bridle to the forestay, and the jib attaches to the front beam. It zips down to the bridle attachment point, then is free to the front beam. Some of the G-Cats forestays were a little short, and most people tied them to the ring on the bridle, using this line(spectra or Vectran of course) as thier mast rake adjustment. Just get the mast straight up and down for now, when you take it our for a sail, then we can talk about mast and rudder rake. The jib has an external halyard that we cleted off to a clam cleat on the side of the mast. I suggest upgrading this cleat to a new spinlock. Attach the boom, raise the sails a nd gor for a ride. Frank Larson used to be a G-Cat dealer, and still has some parts, but I dont know how to reach him now. Google search him, he may still be out there. Hans still has parts, molds, and extrusions. Go to www.seacats.org and click on the links for Hans' site, I cant remeber it off the top of my head. Ill send you the G-Cat 5.0 diagram tomorrow.
BTW, the G-cats had 3 different rudder styles. Which one do you have? Describe it in detail as all are similar, but thier is one that is the best.

David Mosley
www.teamseacats.com