This is a PIA to do but your answer will be in the parts books which you can view on line but not download.
Generally engines of the same capacity will have a common block .
The commercial ones will have bushes & bearing fitted and the domestic will have shafts running directly on the alloy casting.
If they are the same then the blower housings will be interchangable although things like the carb might also need to be changed as it might foul.
I have fitted a few Donaldsons to mowers that never had them from new but I never bolt them to the blower housing as it makes removing the blower housing more difficult.
If you are fitting a bigger & better filter because of all the dust then you will also need to remove the blower housing more often to clean the cooling fins .
I usually fit then to the ROP and then use a length of convoluted rubber tubing to connect the filter to the carb.
Fitter high on the ROP, most Donaldsons I have fitted or repositioned have never needed an element replaced, although I replace the outers every 2 years on the commercial mowers.
It is amazing the difference it makes having the intake 1' higher makes and in some mowers the filter is better than 2' higher than the top of the engine.
On mowers without ROPs fitted I mount it on top of the mudguard ( fender to some ) in a position where it does not get in the way when the engine is being serviced which is usually the starter motor side.
I did a couple of Time Cutters by bending some flat strap up the inside of the guard high over the top then down the other. This makes the guard difficult to remove but most mowers will never need to this.