'Sport' mirror bracket spacing
 

This is a bit of an odd question...but here it goes

I bought my '80 with the 'Dumbo' mirrors (actually, one looks to have been from a van, but I digress...) but there looks to have been other mirrors installed in the past as there are several mounting holes.

I plan to put on the rectangular sport mirrors, and would like to know (if anyone has a pair handy) what the spacing is between the bolts for the bracket? I'm starting body work/filling in holes soon...

Thanks!