Homebuilt V-gate like shifter

Hi, its my first post in FABO
I'm from Brazil and I have 2 A bodies. A 4 door dart and a 2door dart.
Our A bodies looks like some 68 USA darts and Swinger.

I'm building a custom 3 speed inline shifter...

I thinking in "how to fix" the shifter in my gearbox.. my 3 speed gearbox dont have any fix pointing..

any suggestions? weld a plate in the gearbox?

take a look at my shifter...