More times than not, a spun rod bearing block will also have heavy scoring on the mains as well, including the block. The problem stems from the oil supply and crank whip issues as the one or two rods try to twist the block apart, as the mains try to hold itself together. The main bearings end up walking around a bit. It really just depends on how much the engine was run while the bearings were seizing up.
Check the mains of the block for any grooves. If there are any, the block will need to be align bored. Color it cheaper to find another block in many cases...
