I always believed a girdle prevents flag poling of main studs, which causes blocks to crack from reverberation. I had cap walk in my 472, running too 6800, 10.60 @ 126. I swapped in a girdle and aluminum caps, never saw it again. Engine ran to 7k once it got better heads. For $400 and no machining, even if its minimal I'd think it's money well spent.