It's tight yeah, but if you shave the outside corner of that wide spine edge (just a diagonal angle, doesn't affect anything) the arms will fold in fine. Yes, in that position you can't leave the doors on the arms. But remember the arms are reversed anyway, so the doors would be attached as if you're looking at Classics BB from behind. Better to store them inside the body. You can of course just leave the shoulder parts as he comes, it's by no means terrible, just slighly lower arm placement (mine was like that initially, it was only after noticing the off-centre ball joint that I decided to try them another way).