Small Engines (Lawn Mowers, etc.): Motor replacement for murray tractor, briggs stratton, shaft diameter

Question
have a murray mower with  Briggs & Stratton 16 HP Twin II IC motor  Model 402707, type:  1240 01   code:  9412095b.  What other motors/engines can i use to replace this motor ?   I am looking at a  B& S  14.5 HP an a B&S 20 HP, anyone know if they will work, or what motors will work>>

Answer
Both engines should mount but you have have to purchase an alternator/charging system adapter.

The important things to identify is the cranshaft output shaft diameter and length along with the pysical size of the engine...will it clear the engine hood.

For more information on the alternator you can visit Briggs website and search for alternator or charging system.
Any Briggs dealer should be able to help you identify which enigne will work...they have access to the engine sales manual which provides all the info on your engine.
Let me know if this helps.
Eric