The thing with the phantom feedgate, while it is free, you need to make it fit. So yes a dremel wheel will make it work, but if you don't use an adhesive of some sort, it's going to pull right off.
The best route, if you are going the stockclass feedgate route is to pull the top tube off, and move that tube down a few inches toward the user. This would provide a better feeling stockclass tube and more grip for the feedgate instead of cutting it. The downside is that well, you'd have this awkward feed hole somewhere in the ball stack instead at the end via rock forward or rock back.
This is the best...
but at this point you're best getting a super stocker instead of having a beater pgp to mess around with.
At the end of the day, the less intrusive and best way (although not free/cheap) is the PPS speedfeed.
Hell, buy a piece of brass pipe, slot it, bend it slightly and make it old school feed.
Bottom right piece.