yeah, that is the issue.
it falls flat if the pick up gets uncovered.
I went with a surge tank instead of cutting up a new tank or ordering another.
http://www.robbmcperformance.com/products/powersurge.html
this one includes the pump so it is a pretty good deal.

I didn't use that one, because I didn't know about it when I bought mine.

I used this one.
https://www.usrallyteam.com/index.php?main_page=product_info&products_id=1524
but it doesn't come with a pump.
I also don't recommend it, because it is a pain to put together and take apart.

This does mean you need 2 pumps, not just 1 however.
you need a pump to feed the surge tank.
I put mine together so if one of the 2 failed, I could replumb the system to at least limp me home.

now most want you to mount it in the engine compartment.
I put mine above the rear axle instead. both the feed pump and the surge tank.
I suppose mine is skinny so it lends itself better to that.
there is another cheaper one, but it is made out of plastic. bothered me a little so I don't think I bookmarked it.
but there isn't any pressure in the tank, so it really doesn't matter. Just a personal choice.

I was wrong, isn't cheaper,
https://www.summitracing.com/parts/...Jo0jlbuwnBIH2cIbPjb8tK_x85BoClVYQAvD_BwE

name branded though.
they wanted you to be able to use the original mechanical fuel pump to feed it and it would feed the efi setup if I recall correctly.