Look on the valve covers...one of them (I believe the passenger's side, but if the covers have ever been pulled, it could have switched and now be on the driver's side) will have an emissions sticker in the center. The sticker should tell you whether you have a standard or a high-altitude engine.
That said, if your injector pump's ever been changed, it's almost certainly a moot point. The injector pumps on the high-altitude engines were turned down in order to keep from melting the engine due to a lack of air, but most replacement injector pumps are calibrated for standard engines...
Welcome aboard, BTW
