Those polycounts are only vague guidelines - don't take them as rigid limits. Some better guidelines I think would be:
1) Try to bring the model to life, and use as many polys as it takes to make it look built instead of modelled.
2) While you should put on as much detail as you like, keep it within reason for a game engine. For example, hundreds of thousands of polys on a capship would be just as unreasonable as thousands of polys on a nav bouey or cargo crate.
3) Keep it UV mappable and texturable - this is 100 times more important if you don't plan on UVing/texturing it yourself. An 80 000 poly model is pretty useless if left untextured due to it's shear complexity.
4) Keep the smaller detail as modular as possible, and separate from the hull so you can put it into a detail boxed subobject for improved in-game performance.
5) Don't worry about older computers when dealing with polycounts. This may sound like I'm blowing them off, but what I mean is that it's FAR FAR easier to rip extra detail off for lower end versions than it is to add detail later when the still relatively low poly ship sticks out against the rest!
Nice work on the orion btw.
