Not sure I can really help you that much however, I think a lot of airlines vary. The one I work for required a type rating and took me on with only 15hrs on type.
To be honest, I am not really sure why some of them impose a certain number of hours for first officers. Guess it makes sense if they want to fast track people to command. If its just cause they think they will fly through line training it often isnt the case. Its tough to break old habits. I line trained as fast (and faster than some) as the others employed at the same time as me. All had several hundered + hours on type except me.