rsscoggins, I used 2/16 inch gauges - pretty standard for individual gauges.

The modification to the dash area where the radio went was a lot easier than I thought. The first thing I did was to remove the plexiglass that has the holes in it for the radio. The plexiglass just snapped in using some push type retainers. Next, there was a bunch of hex heads screws that holds on the aluminum plate to expose the speedo, etc.

I took some sheet metal from an old fender or door I have and cut a rectangle the size needed to mount it where the old radio went. Obviously I made it bigger - big enough to meet the 4 holes I found to screw the plate down when I was ready to mount it. This plate was what I was going to mount the gauges to. Next I cut three holes the size of the gauges in this plate. This was the hardest part of the process since I needed the holes to be just the right size and to be lined up just right. It took me two tries to get it right.

With these holes cut I mounted the plate to the speedo assy. I then temporarily mounted the gauges to the plate and laid the aluminum cover back on the speedo assy. This let me see how much trimming I was going to have to do to the aluminum to turn the rectangular hole for the radio into three round holes for the gauges. With a little trimming at a time I was able to round off places to make the rectangular hole in the aluminum look like it was made for the gauges.

When I was satisfied with the look I painted all the pieces.

Finally I went to the hardware store and got a piece of plexiglass or lexan and used the original plexiglass as a template to cut out a new one without the holes for the radio. Again it took me a couple of tries to get it the way I wanted it, but a pretty simple process. Once all the mounting holes were drilled I put it together.

Good luck with your modification.