The girdles may provide some lateral stability but darn little virticle. Look at the block structure of the latest performance engines. Deep skirted blocks that do something. If I was going to build a girdle it would have a very tall structure , like three inch or maybe even more. Rather impractical though, hanging a three to four inch tall girdle on the block to transfer more of the load to the pan rail, which might not be strong enough to hold up . But it would help resist virtical forces a lot.