I never used one (YST) myself, but folks I know who did had not chamfered the shell and hadn't had any problem with the BB...so far. I don't doubt that it's a pretty inferior product. My preference would be to rework a replacement spindle to get it to accept the cartridge bearings and snap-rings...just a little work on the lathe is all it might take.
if you can measure all 3 dimensions of the Lambert hub bearing, you should be able to source one from one of the bearing houses that carry a huge stock, like this one
www.bocabearings.com
unless it's a very oddball size: I couldn't find a replacement needle bearing for a Zeus pedal set, but was able to stack 2 cartridge bearings to make a work-around.