can be done, but much better idea is to get some Garrett 2860-9's straight bolt on factory replacement and will be morjust as responsiveas the rebuilt/hi flowed standard turbos.
There was a mob on ebay selling direct replacement steel wheels for GTR turbos, but I never heard of any good results with them.
A rebuild on the standard turbos will be similar money to the -9's anyway, which are good for around 320rwks on pump 98
any way I hope I havent confused you