Sumped tank or fuel cell?

On my last trip to the track, I finally ran through jet tuning on my Holley and discovered that I may have a problem. I ran through sizes from 72F/78R to 84F/90R with a power valve in the front and only found a total .5 MPH difference through the range. With the biggest jets I put in, I would've expected it to be blowing black smoke like a tricked out diesel, but it seemed fine.

I run 1/2" line front to back with a big 100 micron screen filter before the Mallory 140 electric pump, which goes to a Mallory bypass regulator at the front of the car with a 1/2" return line. From the regulator, it goes through a good sized 40 micron filter and -8AN braided line before going to the -6AN carb line. I'm currently using a 1/2" sending unit, which I think may be causing the problem because the pump has to suck the fuel out of the tank instead of being gravity fed.

I'm thinking that I should either put in a sumped gas tank or a fuel cell. Anyone have any opinions of one over the other? Or is there another electric pump that might work better for this? This is a street/strip car and is about 50/50 at this point.