Here I'm indicating my 30 degree angle to make sure it's the same as what I had previously. The reason I'm doing this is because I had to move my compound (the part of the lathe that turns to do any degree that you want) to make sure it's exactly the same as what I machined earlier.
 

I'm modifying my welding fixture to locate my ball bearing in exactly the right spot. The arrow is pointing to the spot I made a dimple using a 5/16" ball endmill. This dimple is where the ball bearing will rest in. The depth of this dimple now places the ball bearing in the center of my screw.
 

I basically tack-welded this in three spots and then sanded away what I didn't need. The funny looking area under the ball will be hidden inside the hole in the roof. Now let's make a way to thread this into the adapter plate.
 

I'm going to use a rivet nut or riv-nut for short, in my adapter plate. This is a simple process that I've used my times while building my 33 Ford Coupe. Riv-nuts come in all different thread sizes and I'm using a 8-32 for my application. All you do is thread the riv-nut onto the threaded piece sticking out of the gun, insert the riv-nut through the hole, gently squeeze the handle and it will deform the underside keeping it in place. Then you just unscrew the gun using that knob on top and you're finished.