it's already got a 3 speed fan. since it's not ECM, I assume the low speed tap without the outdoor fan load will run at a higher RPM than before, so i likely won't want it faster than that. the other issue with replacing the inside fan is fabricating a mount will be more difficult.
to entertain the idea of an indoor fan swap, i'd need a high ambient rated fan motor, since the fan is after the condenser and heat strips when in heat mode. if both are active I anticipate 50C+ air temps.
if I abandon the idea of a used fan for the outdoor half and pay full price, this may suffice:
https://www.supplyhouse.com/Packard-...ly-w-Fixed-RPM
however i will also have to abandon the idea of reversing the airflow through the condenser for ease of cleaning. it will have to push out through the condenser as it's only rated for 40C.