Hey ,
Based on your pics of this engine ,of course it was rebuilt .These pistons are aftermarket and Not Nissan OEM items ,based on the balancing pads .Your crank measurement seems odd or did you mean .0007 (7 ten thousands ?).If you want a correctly built engine trust the machine shop to measure the bores for roundness and taper .Anything less than perfect ,and your engine will Never be perfect .I boils down to what you want and expect from this engine / car when finished .If your alright with it burning some oil ie., quart every 1000 miles ,or do you want it to not burn a drop between changes ? Maybe a new set of .020 pistons fitted or maybe have to go to .030 in aftermarket pistons again or get factory .040 ( Nissan only offered pistons in .020 increments )to have a perfect piston clearance (Rather tight at .001) .Use factory rings ,NPR ,or Total Seal for the best ring seal.Do Not use Cheap cast Rings .The crank probably needs to be turned .010 /.010 is your measurement is in anywhere in the ball park .
You didn't mention the head condition ,but you Must have New intake seats installed (Steel ) if it still has the stock brass junk ,set up
with the correct valve stem heights ,all equalized .
Good Luck ,
Steve
www.risingsunperformance.com