I need some tips and ideas on finishing up the rest of this projects. These gauges were salvaged from a 1952 Willys Overland cab sitting in the woods west of Wadena on my Uncle's land. Because the speedometer sticks out about 2 1/2" from the back, I plan to box in the back so I can set it on a shelf or mount it on the wall. Dash bezel part may look funny but I have to drill the holes for it, and speedometer on my Walker-Turner 900 DP.
1) First I am working with .25" of thickness to secure the gauges from the back. Too short for your average screw. What would you guys suggest to secure it with.

2) What do I seal this maple with? Use what for stain/varnish?

3) Prefinish sand at 150 correct? Then 250 or 400 after final finish?

4) How would you secure the boxed in frame for the back to the front?]

This was my own and last project from college after finishing up my extra classes to complement my BS degree.

Thanks