This is a bit of a hyjack going towards the end goal. You might be doing a low-pressure carb fuel system. My current carb fuel system consists of a steel sump with two bungs welded into my stock tank. You're doing in stainless what I previously did in regular steel. I'm redoing everything more along the lines of what JBC426 is doing. The end goal for me is to have a E85 EFI fuel system that can support 1000+ HP. I have the Stainless Steel version of the OEM tank https://www.classicindustries.com/product/all-years/plymouth/barracuda/parts/ft6020c.html I also have an expensive chunk of 15" x 10" Holley Hydramat. For a fuel pump, I have an in-tank Aeromotive Eliminator fuel pump. The Hydramat is big enough to have one end sit towards the front of the tank to suck fuel when there is under a gallon left and I'm cruising around town. The back of the mat is far enough towards the rear of the tank to catch gas even under a couple of G's of acceleration force and 1/4 of a tank of gas. So the pump won't suck air under a hard launch and it will suck the tank dry under normal driving conditions. I have a methanol/gasoline compatible fuel cell gasket. I need to make an access flange that I can weld onto the tank and then a plate to mount the pump, vent and return lines. I have a guy near me who has a business that specializes in building custom stainless steel exhaust systems so he's going to do the welding for me. The fuel supply and return lines are a mix of -8 stainless hardlines and Fragola -8 (true 0.500" ID) Race-Rite PTFE hose. One other thing that I will include is a Motion Raceworks bypass flexfuel housing in the return line. The flexfuel sensor gives instantaneous % Ethanol and fuel temp. The in/out line for the OEM GM flexfuel sensor is -6 which could be a restriction. Motion Raceworks sells a part that captures the sensor lines and adds a parallel path so that the combined path size is -10. I know that this is a lot of work to put together and it's been pretty expensive to buy all the parts but I want to spend the $$ once and not have to re-engineer the system. I'm not sure what specific alloy SS the tank is made out of but I figure that can't go wrong with making the custom parts out of 304 stainless so that's what I purchased. Photos are not all the same scale.