Cluster size

they taper down a bit on the LH side even the rallye cluster does. the bottom is straight across. i would make all my dimensions from the lower trim going upwards to make sure the gages are straight across.

heres a pic of the template i have made from cardstock for my barracuda rallye dash to put a custom gage setup in. i made my measurements from the bottom edge going upwards so they would be straight across. look at it to the left side you will see a slight taper here too.

hope this helps.
Matt