I just ordered a used 2002 Camaro plastic tank and am also wanting to cut a fuel pump access door while my interior is out. I haven't seen much information on what size and shape I will need for an access door when using a 4th gen tank and pump module and also how to adapt the pump module from the 4th gen to the lines of a 3rd gen.

Anyone have any info on these questions?

 

You really dont need it. The tank drops very easily since the filler neck is rubber and flexible so it’s literally minutes to get down and up.

but if you do, the tank opening is abit larger than thirdgen but the fuel lines are plastic and on quick disconnects unlike thirdgen hardlines so its easier to remove and maneuver

 

Detroit Speed sells a kit that lets you have a sealed cover fastened down with screws.

That plastic tank has a pressure regulator integrated to the pump assembly at the return nozzle inside the tank. I think you're building your car step-wise with the final iteration being a supercharged stroker LS. Now is the time to ditch that regulator and build the full-flow return fuel system you're going to need for that engine, pressure sensors, and fuel quality sensors for alchohol content.