If it were me I wouldn't be thinking of wood or metal to build the dash - much too difficult to get the curvy shape I'd want. My approach would involve a big block of foam, a bread knife, sandpaper and some fibreglass. A lot of time and a lot of dust later and you could have something like this:
What type of foam would one use for this?
Bontragers and rv surplus had complete dashes that were really nice set up with instrument clusters, I don't know what they want for them or what is set up as far as the instrument clusters were, I don't know what they were, but I noticed them and thought they looked kinda cool. Probably from a monaco or something like that.