Cat 1 for sure. That x700 will break Cat 0 implements. Like you said, Cat 1 stuff is also easier to find. I'm not sure how set you are on having it run with a 12v actuator of some kind, but you could potentially add an extra hydraulic valve to control the rear and just use a standard 3 point from Deere. They're super easy to take off and put on.
I'm not sure what all you're wanting to do with it, but my 4' box blade with 4 tines will stop the x748 in the right soil conditions.
I'm not sure what all you're wanting to do with it, but my 4' box blade with 4 tines will stop the x748 in the right soil conditions.