[6pack] Question on speedo & tach light colors for '73

[Cregg Cowan]

A few months back I bought a '73 driver.  It came with the wrong tach 
from an earlier style dash (wrong number font and pointer), but a 
correct-style tach was in the trunk --- it has a broken pointer/needle.  
Recently the odometer stopped working and I'm planning to get the speedo 
repaired and want to get the correct tach repaired as well.  I notice 
that the speedo has green "domes" for the instrument lights, as does the 
wrong tach.  There's a small area of green paint on the inside of the 
case.  The "correct" tach has blue "domes" with an area of dark (black?) 
paint inside the case.

I think the instruments would look strange at night if the speedo had 
green lights and the tach had blue, so I'm thinking of having the tach 
face with the correct font installed in the case with green domes and 
paint.  Is there any reason not to do this?

More generally, can someone explain which models should have which color 
domes in the speedo/tach?  Inquiring minds want to know....

TIA,
Cregg Cowan