I wouldn't run anything bigger than Comp's XE262H cam. I am personally running the Comp XE256H grind in my truck and run 15.3's in the 1/4 with 3.07 gears and a 29.6" tall tire. The truck is so overgeared, I cross the 1/4 mile in 2nd gear and still have rpms to go. With new gears, the truck would probably do mid-14's. In a vehicle that heavy, you need torque. Run the smaller cam. My 350 will run 5500 rpm with the cam it has. That cams you are looking at are built to run 6500 rpm. If you go much over 5000 rpm on a worn out, stock bottom end, you will be spitting rods out and breaking piston rings in short order.