Bike Pro is a dead website. You can find Sachs eight speed freewheels on ebay, and elsewhere, but the selection is pretty limited. Shimano also make eight speed freewheels (fitted to the giant ocr 4 amongst others), and the quality of these is supposedly pretty good.
I was going to do more or less the same, with a full Sachs group, but the ergo levers were too hard to get. Pity...
You could probably get a cheap Campag 8-speed rear wheel from somewhere. Miche still make the cogs.