Just add subframe connectors to a uni-body car and you have a full frame. Then add the cage and you're done. I'd want the front down tubes to hit the front subframe somewhere near where the front of the leaf springs mount to the car since that area isn't designed to carry any load. That is the big problem with doing a straight axle conversion, the load is put into the front subframe in places that the factory engineers were not expecting. So it all has to be beefed up, especially if the guy is going to be pulling the front end off the ground. If you don't have subframe connectors and the proper cage structure the front of the car will bend.
