Airbuses have far higher commonality than older aircraft. There are very few differences other that engine type and some switches (external lights) on the overhead panel can go either way. Newer airbuses have newer FMC's which are much better. Most foreign airlines get "the full Monty" instead of getting dumbed down ones that UAL typically bought. Full thrust engines, and higher gross weights. The engine thrust can be derated through software, and weights can just be limited to the rest of UAL's fleet.

I just don't see much "conversion" work for any Airbus from anywhere. Just delivery inspections, and maybe different FMC's. Maybe HF radios? UAL's Airbus's are bare bones compared to what is available.