"I was going give my guy my spare claim shells to do the same, but Andy might hav this covered. I think the clam shell project will have to be thought out as far as weight of the gauges, where to run wires, how many gauges, are the clam shells secured well enough to support all this".
Agreed, and think that a 2-1/16" gauge is fairly light and fits inside the sight lines of the tach and speedo. The proper angle for the gauge would also need consideration.
"One gauge, sized 2 1/16th would be ideal for me and I doubt you'd want to go with anything larger or more than one considering the positioning of the tach/speedo".
I agree completely with this statement. Boost, air/fuel etc, right in the central line of vision.