I I don't know about a big block. But I can tell you on my small block the main bearings looked 100% better on tear down after the girdle than they used to.

I used to see the outer 1/3 of the main bearing right down to the copper, opposite of the deck.

Meaning the block was flexing all over the place on the power stroke.

Now that has been greatly minimized since the girdle

Small block 360, 1/2 fill, 800hp+. But same principal.