Fuel line vent
 

Hi all, replacing lines and fuel pump on my 2000 LS 4 door. I ordered pre-bent lines, and ac delco fuel module so I'm good there. The vent line is pretty bad too, I am most concerned about the part from the check valve to the rear area up by by the back brake hose. It is a steel section that I cant really follow because of the frame rail. It is pretty rusted, should I leave it be or replace while I am there. Can I use rubber fuel injection hose or should it be steel. Only asking because it appears to change back to plastic at some point.

Thanks for your help
Mike