JDL,
Lots of good advice here. If you have a drill and a driver self drilling/tapping screws may be the easiest/cheapest way to do a temp repair like Rob said. I had to undo some previous welded and riveted work on my truck not so much fun. I also used the screws to hold parts like my rocker panels and cab mounts in place for welding. They are very cheap and remove as easily as the drive in.
I am so impressed to see someone your age tackle a project like this. I wish I started earlier in life. It will give you many hours of enjoyment as well as an appreciation of the history and evolution of american iron. I wish you all the best.
Now get some pics posted so we can see your project!