Hey Lazs, what's your preference of motor? Chev 454 block or Ford 460? I have a 460 in my '97 F250 and its very strong. I didn't buy it for the gas mileage as I only put about 2000 miles a year on it, but the thing can pull a house off its foundation...
I KNOW THIS WASN'T DIRECTED AT ME, but........
the 454 chevy is very reliable. it makes pretty good horsepower, depending on the year you're talking about. i don't think it's very torquey though, as far as a big block goes.
the 460 ford, has always been a torque monster. depending on the year(again) it can make some good horsepower. it, too, is a very relaible engine. it's somewhat easy to work on, but it, along with the 390, has a tendency to burn out the exhaust manifold gaskets.
still, given the choice, i'd take the 460.
just my 2 cents