RE: A bunch of questions....? which .243 rifle for antelope ?
If going the custom route and wanting what you claim reloading will be a must. I assume you either do that now or plan to by your potential cartridges listings. As far as which one I can't really say, no interest inthe .24's. I'll leave that to those who have knowledge.
However in regards to the custom portion canget a donor action (which ever you prefer or like) then have it built to your specs and get exactly what you need/want.All you need is the right platformnot the exact chambering and build away.