It is not a big deal to increase the size of the hole in the floor or make a new one, when I switched to a split master last year on my 46 I had to make a new hole 4” further back from the original, just cut a hole 1/2” smaller than you want, take a hammer and work around the hole gently tapping the edge over to create a 1/4” flange at 90 degrees, I used a SS plate with center screw from plumbing supply (clean out wall cover) to seal it. I could have made hole same as orig and used another orig plug but I wanted big enough for my hand to fit… In the pic u can see the hole and the cover next to it. Electricians have knock out seals in various sizes, plumbers have stainless clean out wall access covers…..to each trade his own……
