Fueling & Injection - Fuel System Question

OK, here is what I have:
5.3 from a 2004 Tahoe, stainless steel tank with a stock f-body fuel pump installed. I am going to use the truck manifold.

Here is what I have been told by a shop that specializes in LS-1 installation in older Corvettes:
Run a -6 fuel line up to the engine with an in-line filter installed. Before the filter install a tee and route a return line back to the return connection at the tank. The middle connection at the tank (5/16" dia ?) will be routed to a small vent filter. Use a vented gas cap.

At the engine, there are two connections at the fuel rail. One is 3/8", that is the feed line. The other line is 5/16" (?) and sets just above the 3/8" line. Is that suppose to be the return line to the tank? Can I cap that if I am running the return like I explained up above?

I am hoping one of the fuel experts here can tell me if this is a good plan, and hopefully tell me what the small connection is at the engine fuel rail.

Thanks for the help.

The 5/16 line at the fuel rail is the return line.
The fuel pump connections, the left hand is the fuel return, the right hand is the
pump, the center is the tank vent do not block it off.

Do I need to run a return line from the fuel rail if I am installing a tee and rerouting a line back to the return connection at the pump? Isn't the pressure reg in the f-body (2001 TransAM) fuel pump?

Yes cap the smaller fitting on the fuel rail if you are using the factory fuel bucket system , the factory is set up just like you described , the Fuel pressure regulator is built into the fuel bucket housing so there is no need to go all the way to the fuel rails .

Thank you sir, that's just what I wanted to hear.

Plumb it like this.
Yes.

Does that pump/unit have a built in regulator on the return ? If it does not, i am not following the idea behind routing pressure to the return first and Teeing out of it.

Does that pump/unit have a built in regulator on the return ? If it does not, i am not following the idea behind routing pressure to the return first and Teeing out of it.

Yes, The fuel pressure regulator is in the fuel pump module.