carrying up front

Just a quick note. You're putting 300 to 400 lbs on the front of your truck. However, your fulcrum is your front axle. So even though you're putting 300 lbs on the front of the truck, you are also going to pull a few hundred pounds from the rear as well. So you may be putting an additional 500 or 700 lbs on the front axle of your truck. It'll help spread more pin-weight to the front axle and give your rear axle a little relieve, but you already have a heavy engine on the front tires. Also note that you will have yourself and anything between the tires putting some weight on the front axle as well. Check how much overhead you have.