I didn’t use any angle adjusting tool, but I could see how it might help speed up the adjustment phase if you end up in trouble. I totally didn’t need it. I did try and mark the linkage rod bolt locations of the stock shifter, but lining those up with the short shifter didn’t really work. So, after install, I left the linkage bolts a little loose and pulled the shifter back into a position that felt natural. And then, I kept rowing it through the gears (especially first, reverse, second and sixth) to make sure I had a full range of motion. Within <5 minutes of adjustment it all felt really good…like I was 98% there. So, I left it alone and was happy with things.
I haven’t driven my car since late October but started it up and drove it last weekend. The shifter really good. Maybe I got the adjustment perfect after all…
Have fun and post here if you get stuck or something.