Should be just one bolt to hold that panel , the top will be held down by the dash. Put a strip of rubber there to make it rattle free and under the panel similar to what the dash has.
Dash fitment,move things around back and forth till you get there. Make spacer if you have to.

 

Also, you can buy replacement rubber for that dash, didn't see any in your pic

 

I think the idea about the rubber is fine. I keep an old inner tube around for special occasions. I will fix it up for now. But in the near future, I am going to get an Inferno one piece dash and a speedo with a tach! It is killing not knowing what RPMs I am turning...



I will order these parts from J&P

 

No trip meter??

 

Almost bought that dash but was concerned with chrome not lasting on plastic, happened to me with a plastic tail light a while back, I guess I cleaned it too much.

 

If that is the same speedo J&P sells, it does not have a trip meter, and the tach function apparently sucks according to the reviews. I was looking into the speedo myself, but decided against it.

 

My bad, that's the $200,die cast inferno. I was looking at a few long ones, others plastic/ cheaper.