Did you add a protection PCB to the cells? Otherwise I don't see how they could get longer...
Yeah, I added a protection board (1.7mm). And I applied insulation liberally (.3mm each layer, with a layer of electrical insulation tape in between).
I did some calculation, even if I repack my 18650, I still can't squeeze it down to 69.3mm, but 69.9mm is a possibility (a very helpful candlelightforum users "RI Chevy" tried squeezing the max for me).
Top side: Flat top cover 1.5mm + insulation 0.3mm + wire 0.7mm = 2.5mm
Bottom side: protection board 1.7mm + insulation 0.3mm + wire 0.7mm = 2.7mm
Total = 5.2mm added with single layer insulation, plus 65mm for the cell, that is 70.2mm.
So if I can flatten the bottom-side wiring and make use of the vertical space of the protection board to route the bottom wiring, I could fit it.
I am a little reluctant to remove too much insulation. The first time I repacked 6xSony from an old laptop, I noticed my gator clip sparked on occasion. On closer look I noticed a very small nick on the shoulder of the cell's factory wrap likely made when I was removing them from the laptop pack's plastic casing. So, it gets me a bit nervous without at least double lay of insulation.
Another user on candlelightforum "HKJ" did some reviews. He pointed me to a few around 70mm to even 74mm max battery length. I may consider those also.
With Nitecore or the other "longer" ones, I think I would miss my logging and the other features I added to my home-brew solutions. So I am not sure what path I would take...