Bigger bowl may mean moving the base forward
Because the discharge hole in the bottoms of both the small and the larger bowls is in the middle, half the extra length of the larger bowl will be aft of the middle. That means, if your small bowl was tight against a bulkhead, the larger bowl won't fit unless you move the whole toilet forward...and that means the bolts won't match the holes in the head sole any more. The solution: Fill the existing holes (do that anyway, even if you don't have to move the toilet...that makes sure the new bolts get a good bite and the toilet won't wobble). Make a nice teak or mahogany "platform" that completely covers the old holes and the space where you have to drill new ones. It doesn't have to be thicker than 1/4", but if you'd like to raise the toilet a little more (household height is 15" from from the lip of the seat to the floor, btw), now's the time to do it with a thicker piece of wood. If the toilet has to overhang any raised step, make the board big enough to overhang it too...so the whole toilet sits on the board. Finish it nicely...bevel the edges etc, sand it smooth and varnish it to match the rest of your woodwork. Secure the board with screws...do NOT cement it down. The bolts on the next toilet may not match either, and a new board will also be the solution to that problem. Seal moisture out with silicone sealant around the edges. Mount your new toilet on it and and commence enjoy it.
