I will assume that you dont weld or have access to
someone that does... I'm in the process of building a
new pan for my SB to fit my Rampage... I want 5" of
ground clearance(from curb height)... I was going to
add 2.5" to the stock pan but I didnt like the clearance
so I will add 1" to the currant sump depth but add
that all the way to the rear... its pretty easy to
figure out what you are adding... 231 cu inches to
a gal/4 is a QT... when you add length or width you
need to add trap doors and baffles.... of course you
need to build a new pick up(at least I do so I can
have the PU in the rear)