Towing setup questions

[bulkin'up73chevy]

New truck. 78 long bed t350 trans. I will be towing an 8000 lb. fifth wheel. right now motor is stock and can't move the thing worth squat. I am doing all the standard towing stuff that I can think of.

Upgrade tranny cooler.
Bigger radiator.
MSD ignition.
Heavier running gear.

I'm trying to get a good motor setup.

I'm thinking stock crank
flat top pistons.
edelbrock two plane manifold
I understand the stock carberator can get more torque than an bigger with jets is that right??
I have 194 heads (possible port these??)
bore motor out .040
280/280 cam.

what would be a good comp. ratio for this.

or am I completely off of where I should be??