In dash tach

[pdxhall]

I have an old sunpro tach that I want to install in the factory location on a gauged dash that I picked up. For those that have done this, do you remove the front faceplate from the tach before mounting it or leave it on? This tach hooks up just like an original but for 2 problems: with the faceplate on a slight modification will be needed to the guage front plate (the lip on the flat of the half circle opening would need to be cut back a little. But, if I remove the faceplate on the guage, the shift indicate arrows have nothing to attach to. Here's a pic of the tach.