I bought my '69 T50 two years ago with rusted hydraulics. I honed all 8 cylinders, 2 for each brake, enough to remove the surface rust but not enough to get absolutely all the pitting. When reassembling them I coated the rubbers and the cylinders with silicone grease, pistons still fit fine. One cylinder of the 8 leaks enough over the winter to drain the master. If I check it once a month no bleeding is needed. The point being that I really only needed to replace one of 8 instead of all 8, at $100 each.
