It's a good feel out process, no? Especially if he's going to play at the PF with a George - Hayward - Horford - IT lineup, he'd need to put on some mass.
So if he can move and jump somehow okay while carrying 270, he could probably be good at around 225-230. Of course it's just one experiment and putting armour is different than actually carrying your own weight, but it's a good "good to know" thing.