I understand. I don't know who these guys are helping you and have no idea of their skill so I'll tell you how "I" would do it and you can relay the info. Because my way is the best way.
Once they make a plate that matches the triangle plate on the shifter, of course they'll heve to drill the three matching holes on each corner, like the shifter, so it can bolt on the top plate.
Next, they should cut a hole in the center of the plate that the bottom of the shifter will fit into. Finally position the shifter like you want it and weld it solid on the bottom side of the plate, around the end of the shifter and then weld it solid all the way around the top side of the plate as well. It will be there until the rapture comes.