Supposedly it's easier on the block because the main caps have an very small amount of flex. In my opinion if you're using a factory OEM block to that point you just need to step up and buy an aftermarket block.
Agreed, or a girdle, at least with those you usually don't need to mess with the main bores just machine the tops of the main caps so it sits flush with the oil pan rail.
With the little machining and prototyping experience I have, that looks like a nightmare @RAMM ... just put some rubber washers under the stock main caps to absorb the forces from the crank :lol: