Is there a reason you want a evo 9 maf vs an evo 8? I use an evo8 maf since I'm using the evo ecu which makes things easier for me but wouldn't have upgraded from the 2g maf if I didn't go with the evo ecu. Do you have a way of correcting the maf size with some sort of tuning solution?
I would check the part numbers on both evo 8 and 9 ecu to see if they are different.
The evo mafs are smaller so you may need a new filter, coupler, clamps etc....
Iceman is the guy to get your 1g to evo maf adapter. Bought both my 2g and evo maf adapters from him.