I was looking at bigger cells and was considering the 700Ah Winston and the 1000Ah versions for a 12v pack. The 700ah versions have the advantage of being symmetrical from a terminal standpoint so making the series connection and just a matter of rotating the cells during assembly.
The 1000ah have the terminals on one end and it looks you would need to put them "nose to nose" to make the series connection which make for a long batter pack. Did you install nose-to-nose or did you just make custom cables
I went thru the thread and didn't see a pic, but if I missed it apologies in advance.