Rene,

The difference probably lies in the final drive ratio on the LPT and your n/a.
Running the engine at 3,300rpm for 60 miles a day should not be a problem. Hell, it would probably run all day at 4,300 without incident. Running the engine at these speeds should not decrease its life, unless something else is wrong with it. Lugging it at a low RPM will probably do more damage than the occasional high speed run down the highway.

The turbo is probably geared higher because it produces max. torque at a lower RPM than the n/a engine. Your engine, at those lower RPMs, would not be in its powerband. The gearing in your car is optimized for your engine, and the gearing in the LPT is optimized for that motor, which has different performance characteristics.

For what it's worth, my old '86 240 (114hp 4-banger with 4spd+OD manual trans.) does 2,600rpm at 70mph, 3,000rpm at 80mph and 3,400rpm at 90mph. Fuel economy is about 25mpg on this car @ 195K miles. Not bad for an old square brick. :-)

-Jim