You can take out the old pump and use a block off plate from a 460 to cover the hole.

2nd you want the pump as close to your tanks as possible, i put mine about 1 foot in front of the tank valve.

3rd I cut the line comin down from the filter so it just came straight down instead of curving into the old pump, then used a piece of rubber to connect the two, dont forget to flair them.

i used a holley red pump, dont know how well 3-4 psi will do when you put your foot in it.

i used a splicing kit for the nylon fuel line cut it and put the splice in then connecting rubber line to it and onto the pump, i ran copper line from there out though.