The only thing that might prevent the GP .42 from out performing the OS would be the quality of the parts, then. Years ago I asked a knowledgable guy what the main difference between OS and the OS clones was and he pointed to bearing classification, heat treatment, choice of alloys, etc.
In some cases OS can't be outclassed metalurgically for a competitive price so the under-dogs can try to offer engines that are set to run a little bit harder.....at the expense of reputation for longevity.