The rings look riveted on so thats a no go BUT if your arms are as wide as they look you should be able to take them off and bring them to a machine shop and have them drill and tap a set of holes at 160 or 165mm or whatever length crank arms you wanted to put on. We've done that a few times for special needs customers. If it isn't safe with your crank arms the machine shop i would guess would let you know before sending out unsafe work.