[XLR8N]

How's it going,
The only knowledge I have on bagging a truck is what i read and building images in my mind.
I have an 88 chevy with a 98 front clip on it. 5.7 single cab fleet side. standard.
I plan on totally redoing this whole truck.
Opinions on if i should do the suspension first?
After searching, reading, and gathering knowledge and information I am leaning towards purchasing this:
KP 6 link (bolt on kit with cantilever setup & watts kit)
10 monster notch.
2 inch drop spindle
and a set of art strong arms.I know this is a pricey setup.
but thats okay im not in a rush.
now i want to know if anyone can tell me how many tanks or how big of a tank you can fit under your bed.
i have heard use 2500's in front and 2600's out back. can someone help me out with the tank. i plan on going with a fuel cell in the bed so i am going to take all the junk out from under my bed for room. i plan on running 1/2 inch lines and valves. but should i go with DOT or stainless?

And i also Plan on doing a stock floor BD on it as well.
20/22 or 18/22 combo.
roller motor.
I appreciate any info givin.
thanks.