Originally Posted by njansenv
Not interested in an online pissing contest - typically, I'd expect to need/plan to go one size up in piston size, and replace the valve seats and (at least) recut the valves. If you find the bores are good enough for just a hone and new rings then great. I just wouldn't count on it. In the (non-BMW) circles I've traveled, a re-ring, hone and bearings is not a "rebuild".
Pulling the motor apart, measuring cleaning and resealing is certainly much cheaper and easier. With any luck, you'll find that is sufficient on your motor, but once it's apart you may find things worse than you hope - hope for the best but plan for the worst.
Personal definitions aside, a rebuild is just that. You take the engine apart and put it back together to spec. In the best case, if an engine is new, it's just disassembly and reassembly. If it's in good shape, it's just a matter of cleaning it and resealing it. Some people doing a job on a budget will even reuse bearings if they are within spec.
So planning for the worst is fine, which is why I also said what are some things which will likely need to be done (especially since this car seems pretty neglected). But whether or not it's acceptable by your definition, a rebuild doesn't have to consist of anything beyond disassembly, checking components and reassembly. Anything beyond that is on a need basis (which is also a personal definition - my last rebuild didn't reuse anything but the head, cams, block and crank).