1966 Barracuda Dash Bezel Restomod

I also noticed that on Roberts solution the new gauges are on top of the plastic cover, and on Dartmans dash the new gauges are under the plastic, so I would like to ask same questions for Dartman as well! (What size, how they are secured, is the metal frame still in there..)
Basically I'm interested in any piece of information which could help my on my own project :)