Your just spinning your wheels IMHO what you need to do is un-hook the front brake lines at the M/C and plug it off and then start bleeding the right rear , what i did was opened it up and let it gravity feed and it didn't take to long to get there you can open both the rear at the same time if you want, and once you have it to both rear wheels, hook the line back up to the M/C again for the front and bleed them. JMO and if that don't work you will probably still have to plug the front brake line connection to the front brakes and go to the distribution block and check it there and get fluid to the rears. Then put the line back in the M/C for the fronts and bleed them. JMO Hope this all makes sense.
I have been there done that.
but once you get it flowing to the rear the rest is a piece of cake. And also just to add i really don't think your 70 has a screw in pistons on it either should just press in IMHO. Or mine did anyway. Hope you can understand what i am saying to do if not just ask and i will try to explain it better ok.