What is the horse power benefits

I would have a concern with cutting the mains down over
.300 on a 360 cast crank. I would also be concerned with
the opening up of the 318 block to 2.810. It would be quite
a machining job for me and it would make the skinny 318 Main
caps even skinnier yet. I have seen a 360 stock eliminator car (450HP
or maybe a bit more) break the cast 360 crank in #3 Main. The front 1/2
kept turning and the back stopped = Epic Explosion!!

If you are going to buy Pistons anyway, There are some decent
4 inch cranks that are not a fortune. even a cast one is fine for
most street builds.