Nice work Polyglot! Glad that it worked for you!
Two days ago i went out and shoot some 40+ frames on 70mm. Capacity of my reel is 100" or around 40 frames. I was also thinking about marking the end of one batch and start of second. Maybe I will try with sticking piece of tape on the frame. As for developer I'm sticking to HC110, dilution H, at 100 iso.
As for processed negatives, I simply cut off perforations so I can use 120 negative sleeves, enlarger & scanner carriers.
Please let me know if you see some good deal on 70mm film, PM is just fine, will do the same.