Motor Swap - 15.5--16 or 17hp

I have a Dynamark(Murray) mower with a 15.5hp Tecumseh OHV engine. It is in great shape but has a blown motor. It was run dry of oil and i believe it snapped the connecting rod.

I want to put another motor on it. So my question is do Briggs and Stratton have the same bolt pattern for mounting as Tecumseh and how many shaft length/diameter variants are there in the 15hp - 17hp range? Or are they all pretty similar?

Thanks so much for the help, i'm a newbie here so i appreciate it.

Dave