Well, I went up to Gold's to see if they had the lock lines I needed. After seeing how big the 3/4" lines were, I decided to try just the 6 lines with flares instead of buying "Y" adaptors etc. This is how they worked out.
My first test yielded a couple of small leaks in various joints of the closed loop, which are repairable.
The flow coming out of the flare nozels was moderate to feel, not as thrusty as I thought they would be at 600 ghp each. So I'll stick with them.