Okay, this is from my "little engine experience"
For your purpose, I think a big block is silly. Wanting a gas pig (you may as well hire a tanker to be there for the weekend) just so you can have more cubes than everyone is just dumb. As much as I love muscle, that's dumb.
It's the same concept as building a HUGE rig for city driving, cause big tires look cool.
Edit - By the way, trucks don't "Fly" unless they're rails. If you want a speed demon, build a 71 Nova. If you want a wheeling rig with power, build a 400 horse engine, get good diffs, with good gears, twin tcases, and some 40s and link it. Then you'll have a GOOD truck, and it'll be only a little bit more cash than building a $10,000 motor. Oh, and your truck might actually last 10 minutes.
Most HiPo engines (low cost anyway) get bolted to LoPo drivetrains, and the owner spends $$$$$$ to beef up the rest of the dt.