Best mounting location for new floor shifter

Sorry to jump in here late, but I wanted to chime in. The method above is what I used to mount the same shifter. I sat in the seat, put the shifter in D, and then located it where it felt comfortable in my hand. We welded bolts to the floor pan so as not to drill anymore holes. Here is where mine landed. I am short and have short arms, so my seat is up further than yours.