FWIW, the consensus I found was to use a 15/16 bore rather than factory 1 1/32 when going to manual brakes, at least for my 73. I assume that would also apply to a 70. I purchased a 2 bolt master and adapter plate from Dr Diff and I already had a manual pushrod from the original non-power 4 wheel drums. I was able to easily reposition my NiCop lines to the master as they bend pretty easily. If still running factory lines I think you might have to replace from the master to the combination valve as I don't know that it would be very easy to tweak those steel lines. I will say, if you value original appearance, the 2 bolt is not for you. I have had both rebuilt and new original style and neither worked properly for very long so I decided to try my luck with a newer style master.