Bearing size confusion

[Joelvv]

I'm rebuilding a running engine to replace another engine that went bad. The engine came out of a 1998 Tahoe and has factory 0.0006 US main bearings. 0.001 main thrust bearing. Rods had standard bearings on it. I've had the crank polished, and need to figure out what bearings to order.
Rods measure between 2.0985 to 2.0989. I figure 0.001 US should work fine on those. All will be plastigauged to confirm.
-
Where I'm concerned is the crank.
-
I can't decide if the original 0.0006 US bearings were due to the crankshaft being slightly undersized, or the bore in the block being undersized. If it's the bore in the block, I think I need 0.002 US. If it's because the crank was slightly smaller than spec, I need 0.001 US bearings. The mains measure 2.4479 to 2.4483. @ 73-74F.
I figure 0.001 US makes the most sense for the crankshaft too. What do you think? I like to avoid buying 2 sets if possible.

 

[Schurkey]

The Vortec 5.7L engine I rebuilt also had goofy main bearings, and standard rod bearings. The rod bearings had minor wear, I replaced them with standard bearings.

The main bearings looked so wonderful that I just re-used them--but I didn't polish the crank because it, too, looked beautiful. Seems to me that only half of each bearing was .0006. The other half was standard--but I don't remember for sure.

You'll want to find out if the bearings are +.0006 or -.0006. If the crank is slightly undersize, the bearings will be thicker (called undersize) to take up the excess clearance; but if the main saddles are slightly undersized, the bearings might be thinner (called oversize) to allow a little more clearance. Short Story: You probably need a machinist to measure your block and crank; and then make decisions about what bearings to use.

My cam bearings looked terrible, but the cam itself seemed fine. I don't know if the bad-looking bearings are a "real" problem, or if the stories I've heard about GM align-honing the cam bearings after installation are true. I put new, regular cam bearings back in, and the cam seemed to turn fine.