Ah, here we go. The Unofficial Turbo 601 Home Page:

http://www.brinnoven.co.uk/turbo601/index.html

And similarly for the PowerPro

http://lowendmac.com/quadra/unofficial-powerpro-page.html

The PowerPro information seems to have moved to Lowendmac. It used ot be it's own page with a link from the Turbo601 site, but the link there is dead.