Hmmmm, I just can't see a 5-inch tach in the corner by your A Pillar ... that's going to be an obstruction and a pain in the azz to mount IMO, and your shift light is going to add to the dilemma since it's on the left.
Sounds like it's time to fab up a bracket girlfriend!!! :-D
Oh, and Happy Birthday too! Any other lady who gets car parts for her birthday has to be beyond cool. Forget the 15 pairs of shoes and the mall!!