Rockets should work great with the IIvx PSU, I had a fully loaded one working fine with the less beefy Q700 PSU. If you have any problems with starting the IIvx while they're connected, you can remove a few of the RAM modules to reduce the power draw and the HEAT those things give.
I'll admit I never really figured out what to do with a Rocket. They're awesomely hacky means of getting another Mac in your Mac. Only problem is, the real time multimedia subsystems (QuickTime, many forms of audio playback) don't know what to do if they can't have the highest possible priority on your Mac.
Web browsing on Netscape 2.0.2 might work in a pinch. Photoshop is an easy one, even though any Power Mac can do the same batch processing jobs better. FrameMaker required a decent amount of horsepower too.
Really something that would act as a pint sized "server" almost seems ideal for a Rocket. I vaguely recall that the AppleTalk interop with RocketShare was surprisingly well done, if not always stable.
3x videovision card with expansions. + videovision breakout with video ins and outs.
That uh, sounds like the beginnings of a great Premiere 4.2 rig. Have you considered showing off to Premiere/Final Cut architect
Randy Ubillos, now that he's retired?