OK, so you're not doing a whole overhaul. Pistons are fine to reuse. New ones are VERY expensive, so most reuse them anyway. I'd rethink the bearings depending on how expensive they are. If you postpone the build for a couple weeks to get more cash, it'd be worth it. Rings, yes. Measure the bores for diameter, roundness, and taper before you start rebuilding. If your bores are too far egg shaped for example, you'll use oil even with new rings.
Inspect the valve seats closely. If they're pitted or flame cut in small spots, a lapping might not be enough to get the valves seated nicely. If they're serviceble, proceed but don't move the margin too far off.
Strongly consider replace the oil pump drive components.