I have a '75 CO that I rebuilt and I went with LiFePO4 lithium. I added a induction cooktop and a good sized dc refrigerator and went with a 400ah rack mount battery that hangs vertically in the space under one of the dinette seats. As I'm sure you know, lithiums are safe to use inside and don't need venting. I had to do it again I would have gone with multiples of something like this one that has low temp charging protection and bluetooth. https://www.amazon.com/dp/B0CNVDF15C?psc=1&ref=ppx_yo2ov_dt_b_product_details