Small Engines (Lawn Mowers, etc.): 11hp briggs swapped for 18 hp twin cyl briggs, hp briggs, shaft diameter

Question
I have a 1993 Murray 38 inch cut that has a hole blown in the side of the original 11 hp Briggs engine.I am wanting to swap an 18 hp Briggs I/C engine from a Dynamark 45 inch cut mower made by Noma Industries. Could you tell me if this is possible with out too much alteration of the original 11hp engine bolt pattern, and what about pulley size, belts, would it be too much power for the rear drive, etc...?  

Answer
 Hello Sam:

 Depending on the Models of Both Engines, you can Swap the Engines with Littler Other than Probably Re-Drilling the Mounting Holes for the Engine Mounts. Some Frames are Pre-Drilled to Accommodate Both Engines. As for the Shaft Diameter and Length, that Depends on the Models. As for Power; you will be Fine, No Worries. I have Replaced 8hp Engines with 21hp and 22hp Engines and they Worked Really Well. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks. Be Safe.

 Good Luck

 Respectfully

 John

 PS: Merry Christmas and Happy New Year (:-))