on alt wise, my alt is 70 amps n i done the big three in 0guage n mine flotes around 14.x volts, with air or radio full tilt doesnt go below 13.8, but i just replaced all my ground wires with 0guage due to the fact that they was only 10-12guage n wouldn't of helped any if they was still there or not, but if ur factory grounds are 4guage ied keep em n just add to it, n i just ran a wire from my alt to a fuse, then to a dist block( i have 2 batterys) then to battery pos, n make sure u sand the spot to bare metal befor u do ur upgrade n dont tightin the bolt or w/e u use to attach ur grounds cause the sheet metal is thin n it will strip, i stripped about 3 holes befor i got mine right, n has worked every since
heres some pics of my big three if that helps
from chassis to block
from chassis to battery neg
alt to fuse holder n dist block n battery pos, the round fuse holder goes to rear battery, the other one goes to alt