To jump on Jerry's band wagon about being torque-limited ...
I have a splasher 235 (the big brother to your splasher 216) in my 1-ton pickup. I upgraded the rear axle to a better ratio for higher cruising speeds. In short, I have a lighter truck and a bigger engine than you. But Jerry is 100 percent correct that with aux boxes, rear axle tradeouts, taller gears, etc, you are going to run out of power fast. My truck will cruise at 60-65 all day.... until it hits a hill ... or a traffic light .... and then it takes awhile to get back there. At the top end with a splasher engine, you will just not have any power.
My pickup with a splasher 235 and 4:10 rear axle, from a dead stop, takes just over three miles to get up to 60 mph. Just sayin'
