I like the factors you have used, not necessarily the way you've used them. Especially this one:
"Runs scored by other batsmen in the same team innings, divided by the number of batsmen used."
seems to have some value in it.
I've done a similar scorecard based 11-factor innings ratings:
cricrate | Test Batting Ratings
I average the innings ratings (adding a longevity bonus) over a player's career to rate their careers, which made me have to increase the weight given to runs scored over other factors. That's why the known innings like Lara's 153* and Botham's 149* don't feature right at the top - something I wonder whether is a real issue. Was the 153* really better than his 277, or any one of his big doubles?
If you went with this same formula to rate every single innings a batsmen played, most likely you would find that the accepted ATGs won't feature in the list the way you would expect.