No. You will not need to upgrade to accomodate the added horse power.
However you
will want to upgrade for speed and mpg.
You probably won't want to cruise your 235 faster than 2600 rpm. With stock tires (29" O.D.) and stock 4:11 rear end, that will give you 55 mph. You can replace your 4:11 ring & pinion gears with Patrick's 3:55 r&p (about $400 at most vendors) to get 65 mph at 2600 rpm. Taller tires can bring that up to 70 mph.
If you want to lose your torque tube driveline, you can get an adaptor for your tranny, have a new driveline fabricated, and swap in a newer rear axle of similar width to your current one. You'll have to weld new perches on the new rear axle, and chances are that the lug nut pattern won't be six bolt. For more info read Jim Forbes article at
chevytrucks.org and of course be sure to check out the
Donor Rear End Measurements article here at Stovebolt.com.
