64 GMC - suspension upgrades and questions

[64GMCHorsepower]

I have a 64 GMC Fleetside w/ leaf springs in the rear

Right now I have Drop LCA's on the front w/drop springs....total 4 or 5" drop

I have taken a few leafs off the rear.....total drop of like 3"

NOt too happy with the overall look or driveability, I would like to see the rear a little lower without having to cut into the bed floor..

Sooo,

What are the advantages of a IFS front suspension?
What are the advantages of PB front crossmember?
Do I have to bag them, or can I run coilovers with them? Or is that an option of any kind?
What is the best option in the rear, as far as driveability, and dropping the rear? PB notch? change to trailing arms? bag it?

I don't want to lay frame, but I do like the overall lowered look,,,,,

Any opinions, options, or products you can throw at me will be greatly appreciated......

I'm looking at around 5K for the total redo.....
Sorry for the long post, if you need any more info, lmk

Chad