I am going to start with method #1. If I can't manage I will get some help. I am not even going to try #2. Why not measure from on top of the lash adjuster when the engine is together? I would fab some sort of luck nut with a pad for the gauge pointer. With the engine together you can not get around the arm's radius effecting the reading a little bit but at least you don't have lift ratio entering into the mix like you do on the other side of the arm.
Securing the dial gauge and a reference point for the degree wheel! It gets real tricky!