I use a Z750 to power the repair/test track in my workshop. It's been doing that for ten years or so and it works just fine. One thing to remember - if you get a Z750, be sure it's NOT one of the early ones. The Z750 controller was modified after MTH discovered, to its considerable embarrassment, that the output waveform was not compatible with Protosound-1 and could even damage the Proto-1 circuitry. I don't know how to tell which controllers are the early ones once they are out of the box - I'm sure there's a way but I don't know it. MTH did change the packaging when they changed the electronics - the good ones are in dark orange boxes; I think the early ones went out in yellow boxes.
I agree with Russell - if you're buying a new transformer you may as well spend a few extra bucks and get the Z1000.
