And clearly your set-up making an even more one-sided battle is completely fine because Goku wins right?
Canon is a continuity defined by the current authority of said universe. Since DC has the rights to it and not the deceased writers of the original, they call the shots on it.
Also since I assume the original version falls under the category of "Pre-Crisis Superman" which has been essentially retconned, it's not canon
A fair death battle takes all possible canon sources into account so no details that could change the outcome of the battle are ignored. Your "fair" set-up is basically giving one character a significant disadvantage for being a character far too old to have all comics or movies or whatever being made by the same author. Superman's accomplishments are the result of the compilation of multiple minds towards one goal of telling unique and new stories for a character. Oh let's just use only exactly what he did in some of the original stuff, specifically to stifle all of the actual developments he had as a character, that makes things FAIR because clearly using his modest beginnings makes him the DEFINITIVE superman.