Benedetto is a good place to start, most definitely.
I'm not sure if this is feasible with the bodies you have, but I would seriously consider think about trying a Taylor-style bolt-on (search the OLF), it is basically just a butt joint with a fretboard extension that is routed slightly into the top of the neck block. You can have either screws from inside the body threading into inserts in the neck heel, or hangar bolts sticking out of the heel that you screw nuts down onto from inside the body. There are a few folks who've pulled it off with archtops, basically using a long tool that they insert from the endpin hole or endpin jack hole. Which you may or may not have....and may or may not want to drill.
With the neck you have, you'll need to add onto (stack) the heel so that you make it thicker, then craft whatever kind of surface/tenon/dovetail you need to mate up with the body.
Also your neck blocks may not be set up for a butt joint...a lot depends on what's going on there. But after you read Benedetto, and after you've gone to school on the Taylor neck joint, give it a thought. Taylor-style joint is the way I'll be going on my first archtop build.