Had a few days free so thought I'd try this... 3 days later... I finally got the 69 I was seeking! Better may be possible but... this was hard enough and a 69 is a good reward. I went from 75 to 74 to 71 to 70 and thought that was as good as it gets, but like anyone so close to getting a 69 I had to keep trying...

Sadly I could not make this loop - there may be a way but unlike my looping 70 (now a showcase) I had to remove the lower bonder here as it caused problems with the 2 block waste.

But yeah, 69!