Small Engines (Lawn Mowers, etc.): mower engine replacement, horsepower engine, replacement engines

Question
I have a Yard Machine 6Hp push mower model 12a529n062. I would like to know is possible to replace the original engine with a higher horsepower engine. The present engine is a 6.0 quantum, which is wearing down. The model,type,and code of the engine is 12H802-3509-B1  01012256.
Thanks for any help you can give.

Answer
As long as the crankshaft and engine footprint, the mounting holes, are the same you can swap engines.

Have you priced replacement engines?  A new engine may cost 50% of the cost for a new mower?  Did you orginal engine have enough power when it was new?  

Let me know.
Eric