The foam in the Pelican and Storm cases is either little cubes you pull out to form a custom fit, or it's solid and you cut it with a knife. Either way, it's painfully simple to turn the solid foam forms into a custom fit for your rifle and scope. (I think all the rifle-sized cases are solid foam that requires cutting; the smaller ones have the cubed foam.) I customized a Pelican case to fit 2 1911s and a Sig.
Storm will pre-cut the foam for you if you send them CAD drawings or something. I'm sure Pelican will do the same, but for a one-off application, it really is unnecessary.