This aspect of our hobby has been evolving quickly. Fuel systems have come a long way in the last 5 years, especially for EFI conversions.

Gone are the days of intricate baffles, sumps, fuel traps and/or multiple snow mobile style pick-ups in an attempt to get air free fuel to the motor.

Now, you can use a stock tank, cut a hole in the top, stuff in a properly sized Holley Hydromat and plug the access hole with a fuel cell style blocking plate kit. Done, and it will out perform any of the older technology down to the last gallon.

Fuel pumps can either go inside the tank or outside the tank. Simple.

The latest trend is to use PWI controlled fuel pumps with no return. Return style regulators work well too.

In your case, I would put a flat floor in and mount a larger capacity fuel tank under the floor taking advantage of the extra room you have. Added fuel capacity is nice with a hungry big block.