Examine the crankpin and main journal surfaces for scoring, scratches, or corrosion; if any are evident, the crankshaft will need professional regrinding. Use a micrometer to test each journal and crankpin at several different points for ovality, and if it exceeds 0.001 inch, regrinding is necessary. Undersize bearings are available to match the recommended regrind diameter, typically supplied by your GM dealer with the reconditioned crankshaft. After high mileage, main and connecting rod bearings may wear, leading to excessive running clearance, which can be checked using a product like 'Plastigage' after refitting the original bearings and caps and tightening the cap bolts to the specified torque settings. Avoid correcting excessive running clearance by filing the caps; instead, fit new shell bearings after checking the crankshaft journals and crankpins for ovality and confirming their diameters. Checking connecting rod bearings follows a similar method, and it's advisable to check the running clearance of rod and main bearings even with new installations. The crankshaft endplay should be assessed by pushing the crankshaft to the extreme front position and using a feeler gauge at the front end of the rear main bearing. Measure the connecting rod side-clearance with a feeler gauge between the connecting rod caps, and if it falls outside the specified tolerance, replace the rod assembly.