Slickt,

The only way to accurately know if a shim is required would be to mic the crank. A full rebuild would include rod and main bearings. This means a crank grind, or at least a polish. This involves an automotive machine shop where the crank would be measured and appropriate rod and main inserts ordered.

If the rebuild is done in the garage, the absolute very least that would be required would be a plasti-gauge measurement. This would be the starting point, or reference as to weather shims would be needed or not.

Your '59 engine may have never had any shims on the mains. They are pretty prehistoric in my thinking...but I'm just an old Millwright.

Anything dealing with the rods or mains should be addressed by a automotive machinist and his proper array of measuring tools. Those bearings and clearances are the heart of the engine.

Stuart