Yup - carpenters brace where I live is the same as in US - 4 sided taper type chuck. I didn't do anything fancy to fit the chuck, just machined a round shank on my special socket to fit it.

You definitely don't need 1500 rpm to test the OD function. You can build up the hydraulic pressure to activate it easily at hand cranking speeds. My guess of 120 rpm is based on what I think I cranked it at (2 revs per second) - I didn't bother to time myself. I'll post a photo later tonight when I get home showing the setup if you like. I went overboard and attached a pressure gauge to confirm the hyraulic pressure change but this is not really necessary.

I think it is a lot of effort to setup a chain drive to motor it over. Like I say it does not need to be fast, it just needs a bit more torque than you can get from an electric drill.