Having been there - albeit in the middle of a rebuild - I would have a rebuilder get you another crank (most of them won't ever see enough mileage/abuse to wear out) and have the whole rotating assembly balanced at the same time. New bearings and piston rings, and you should be good to go for a long time. You have everything lying apart already - so even if you get another secondhand engine you will likely pay for the workshop hours involved. Instead of introducing another unknown factor in the shape of another secondhand engine (warranty is nice, but if you get through the same ordeal just after the warranty expires, you're still not happy, right?) doing a proper job on the existing engine -which makes it effectively a brand new one - seems to be the preferable solution for satisfaction and peace of mind.
If the repairer diagnosed a major engine problem before tearing things apart, it would be another matter. Now you're paying for the teardown, might as well bite the bullet and pay for reassembly, too.
BTW my engine builder (Frank at Sweedspeed, The Netherlands) sourced a crankshaft and balanced/shot peened it to motorsport standards) and it cost me all of 300 euro's. A new set of Glyco main and big-end bearings (including thrust bearing) was 110 euro's. Doing thing the proper way on a Saab bottom end is not as expensive as people think (OK, so I had the rods shotpeened and weighted, a 'new' block bored to 92 mm, forged pistons and piston cooling oil squirters installed, which naturally added up to a somewhat more sizeable bill...).