Honestly, the 27cal bullet selection sucks, so even as a handloader, I'd stay awat from that 'wildcat' of a round.
Which brings me to point #2: are you going to handload for this rifle? If not, I'd stay away from anything other than 308 or 223. If you are a handloader, then I wouldn't see any reason why you should feel limited to the aforementioned two calibres.
If you do handload, I'd suggest something like the 7mm-08; 308 case but necked down to 7mm for better bullet selection and better balistics/wind 'bucking'. Finding brass might be a ##### but you could form your own without worrying about your 'noob' status. Everyone starts from somewhere right? I think people will use your noob status as an assumption that you're looking for the easiest, low maintenance option, in which case a 308 would provide you with an infinate source of distributors. Put a little more work in and you could have a calibre more capable and you'll also have developed skills that others wouldn't have, such as fire forming/necking up/down.
If you want something easy, then I'd suggest something like the
6.5x47 Lapua which is similar to the 308 in length and bolt face but offers superior balistics, case efficiency, and maybe a bit cheaper. There are several 6mm chamberings too.
Just stay away from the 'magnums' for now and have fun!
