360 crank in 318 block

Ottmundr said
Here. Save the cost of machining and buy the 3.58 crank sized for the 318/340 mains.

Mopar Performance Cast Crankshaft

It says requires narrow bearings. Can you shed light on that?

Dana67Dart said
Why not just put a 360 crank into a 360 block and be done with it. Much less trouble

He said he had 2 - 318 blocks to play with. No mention of 360 blocks.