Couple of things to be careful of...
First don't forget that the bottom panel is around a half an inch up from the edges and it supports none of the weight. ALL of the cab weight is supported by the sides and front. When you put wheels on the bottom now it is supporting all the weight and it is only held in place with something like eight locking cams. I haven't had any issues 'yet', but I will be re-enforcing the bottom panel soon so it can properly support the weight and have wheels attached.
Second, I'm not so sure the UAII will handle being tilted and rolled well. I'd be afraid of the pressboard coming apart from the weight and stress at an odd angle. I used low profile appliance casters on my UAII.
Just be careful and re-enforce the bottom and you should be fine, but I still wouldn't tilt and roll it.