Agreed; Plastiguage is not reliable enough for a blueprinted build. The only thing that can check a mic is another known good mic. If you are going to push it to the ragged edge then RedHeartbeat's advice is the only one to take, take an extra day and measure/verify taper in addition to clearance. RE crank rotating smoothly is only valid after you've capped the mains; once you begin stuffing cylinders in my experience doesn't mean a damn thing. Several of the most reliable short blocks I have assembled had ring packages with pretty high tension and were very stiff to turn over (50+ ft-lbs after the pistons were in) and I've also had others with low-tension rings that would turn over with 20 ft-lbs. Use a known good mic, you can get a Mitutoyo digital caliper for $50-75 on eBay.

Mr. P.