Seems like I remember an article in a past R & C mag... do you have old ones to look through? Mine are all in Alabama so I can't look or I'd send it to you.
put the body over the frame in the location it will be bolted down. Mark where the body starts. Pull body off and decide if you want the Z to be behind the firewall, middle of the firewall, or in front of the firewall. For the back, simply Z it before the rear cross member. Cut a 22.5 degree angle in the frame at the same location on both sides and put in desired Z length cut at the opposite 22.5 degree angle and weld in with a 220 welder of your choice. Grind welds add salt and enjoy. Oh, make sure all your welds are level and even and that the frame is totally square otherwise the car will be dangerous as hell and "dog walk" down the street. This is not like replacing a patch panel and can go really wrong if you dont have some serious skills. Frames need to be perfect or people die. Paul