So instead of providing a solution, you want to give your opinion about whether or not I'll void the warranty that commercial use doesn't qualify for? Get fucked super star, if you have nothing of value to add to the conversation keep your opinions about what other people do with their equipment to yourself. Sincerely hope you don't breed, the world has enough ignorance.
If this is your level of conversation then please leave and go annoy people on Face book where profanities and abuse belong.
I personally think you are on a one way trip to disaster .
The mower racers all bypass their governors and regularly are here buying new pistons , rods & cams till they decide to cough up for a proper race kit .
The new engines are built from parts that have a precise service limit and for most con rods that is around the 4500 rpm to 5000 rpm mark.
Add to that the decks are designed to run a specific speed and the airflow under the deck will only work properly over a very short rev range.
Then there are the hydros, again designed to run over a very specific rev range and over reving them is the second fasted way to destroy them ( running at load too slow is the fastest way ) .
If you have needed to replace all those items then there is either some thing drastically wrong with the mower in which case it should go back or something drastically wrong with the way it is being used .
As for the Walbro carb, a carb is a carb is a carb is a carb is a carb
A carb atomises a set ratio of fuel into the volume of air that passes through it and that is regardless of the size of the cylinder it is feeding
If it is too small it will limit the WFO speed but will accelerate faster till it gets to its limit
A carb that is too big will accelerate slowly and use a lot more fuel
And that is about it
And considering that it is a mower engine that is designed to run 3500 pm the size of the carb is just about irrelevant .
Most mower carbs are bigger than they need to be and the 1/2 Hp variations are done by using gaskets that restrict the inlet
And FWIW I am currently riding a 500 cc single cylinder motorcycle with a carb from a 350 cc motorcycle and have been doing this for near 150,000 miles.
I really do not know why you posted here unless it was to get considered opinions from the people who fix these things day in & day out about what you are intending to do
And if that is the sace then IMHO what you intend to do is plain stupid, but it is your money so enjoy yourself .