So I mustered up some courage this morning to finally do something I had been intending to do since I purchased both of these around the same time together and saw here on the Customization part of the forum.
I am very happy how it turned out here. I went ahead and used a screw to drill into the point where the female end of the neck connector for the Titan Master (Nucleon) goes. I ended up making it so I didn't damage anything and can easily switch it back if I needed to. My screw was just the right size I used and I drilled in it in such a way that it doesn't hurt anything or cause monumental problems if I were to reverse it. In fact, I noticed the Titan Master fits better into it (and how it's supposed to!) without the feeling of it breaking in your hands when I did my reversal test to make sure.
I'm happy it came out as good as it did from the pictures I saw of it done here in the past. Just wish I could find a system where I can just pop the head off and reattach it when I go to transform him to his alt-mode instead of meticulously unscrewing the back of the Galvatronus head to take it off and put the cannon peg into its respective hole. Something to look into in the future I guess.