Doesn't sound like a bad setup. GM's late model Vortec heads an intake set up are usually transferable to older blocks, so I believe the 8.1 is nothing more than a Mark IV 454 big-block Chevy fitted with a stroker crankshaft, Vortec-style heads and intake. The 454 is a 7.4L, stroker versions were 496 and 502, which came to 8.0 and 8.1L. Good engine AFAIK, its roots go back to the early 1960s / late 1950s, so obviously a tried-and-true platform. The 8.1L will likely have an Allison automatic, but it is probably the weaker AT545.
As already mentioned here, gasoline engines have their good points and bad points, just as diesels do. Two forces are at work here, torque and horsepower. Torque is what does your pulling, horsepower is how fast it accelerates. Diesels are big on torque at low RPM, where gasoline engines have to rev up to make their peak torque. Diesels, in turn, cannot make the same horsepower as a comparably-sized gasoline engine, even with boost.
The trade-off is that a gasoline engine will never be quite as efficient as a diesel, because a gas engine will not make the same torque as a comparably-sized diesel. And more torque at lower RPM will generally make for better fuel efficiency, because the engine doesn't have to work as hard.
"Cheese Wagon" <firstname.lastname@example.org>
Former owner - 1989 Ford B700 64-pass Blue Bird (Rest In Peace, Cheese Wagon)