Can I replace a 17hp murry rideon mower engine with a 17.5hp briggs engine

Hi,
As general rule yes since you most probably replacing a Briggs with a Briggs. There are a few areas that can give minor problems. They are electrical hookups, fuel system, and muffler.
The mounting surface is standardized as is the crankshaft. Provide model and type of the engine to be replaced and I can probably give the factory info on suggested replacement. Give the info on both enignes and I can be more specific about that.
Peace,
Clarke