When I bled my lines Ron Butler suggested removing the calipers from the mounts and then bleeding which I did. The result was two passes and I have a very solid pedal. You may want to try this... Also I removed the lines first and ran fluid thru an open line until I saw a solid stream. Just hold your finger over the line end to stop from sucking air back into the line. It is a two man (not a man and woman) job
. By the way I am sure you know to start with the right rear then left rear. Right front then left front. Adjustment of the balance bar assembly is also important in getting the right proportioning.
Added by edit: If all else fails consider putting a pressurized line into the top of your reservoir cover (I made a special cover you can use) and put some air pressure on the reservoir and then bleed. I had to do this the first time years ago.