I posted this in the LT1 tech section but thought it might get more reads here.

I am in the process of building a fuel system for my fourth gen LT1 and need some help and advice. I have a set of fuel rails that I tig welded and a factory replacement gas tank that I sumped. I am going to use the factory sending unit (lid, bung, plug) whatever it is for the return line. There are 4 lines coming out of the plug. I know there is a feed and a return port but what about the other two? Are they both emission/vent lines? Can I just just weld in a bung and use a check ball like would go in a fuel cell for the vent and block off the mystery lines? Before I get flamed to death I know this is overkill and the racetronic pump is the best thing since sliced bread but I already have a new pump and filters. Plus I like the safety factory of braided stainless and no plastic lines. Thanks in advance. James