I made a couple for my 68-69 RR's over the years,
this last one I did in like 2007 to 2011-ish
about $700 in gauges, $20 in angled gauge pods
{
all Autometer, classic with the chrome bezels 3-1/8" speedo & Tach, 2-1/16" other 5 gauges}
a $20 piece locally, of 0.095 appr. 20" x 4-1/2" piece of alum.
with a 1/2 lip @ 90* for the top attachment
another $25-$50 {or more} in wiring & connectors, solder, shrink wrap etc.
8-10 or so hours of labor, drilling, sanding, prime & painting,
wiring {priceless

},
a can of epoxy etching primer $8 & crinkle black paint $12
all approximate costs... = $780-$800 {2007-2011 dollars}
7 gauges, 5 small & 2 larger
in the order & arrangement I did, is a really tight fit
I could easily see it costing $1200-$1500 to have made
the bottom of the 2 big center gauges rests on the lower dash pad
it's only about 3-3/8" total room, overall size with bezel is every-bit of that
it tapers from left to right about an 1", the right side is taller
{that's the way Chrysler did the dash clusters}
I lined it up to match the lower dash, centered on the steering column
installs in the org. hole, the upper 90* lip gets drilled to hold the top,
use org. holes too, the bottom is held in place by the lower dash pad
the 3-1/8" mech. 160 mph Speedo & elec. 8k Tach
are both flat mounted/centered,
I put 2 green 5/16" LED's just to the left & right of the big gauges,
for my blinker indicator lights
{all little various LED's are with chrome bezels}
It also has a 5/16" blue LED for bright lights, centered
It also has a 5/16" red LED for e-brake warning, to the far left
It also has a 5/16" amber LED for Low oil pressure warning, to the far right
sorry no photos installed