Is it compatible cause the RH ironsights says that it replaces the meshes of guns.

The main thread for those overhauls are the best place to ask questions like this.

for instance - http://www.gamesas.com/index.php?/topic/1094641-relz-fwe-fo3-wanderers-edition-39/page__view__findpost__p__16000274 is a great example of how this very question is only one page back on the FWE thread.

I'd also bet the Arena-FCOM question would get answered more thoroughly in the FCOM thread too - it is in those threads that the authors of the mods and the most knowledgeable users will likely see your questions and often give the best answers.