Paul, the 143A unit will be fine. I would consider a used one, all my conversions have been used alternators, they are typically under $100 shipped. Worst case, you might need a new regulator, but those are pretty cheap. Remember that the remans will require a core, and they usually won't give you credit if you return a different item (i.e., your stock 70A unit).
Anyway, unless you intend to install custom battery terminals or distribution blocks, I would not use a single 0-gauge cable. It's much easier to use two 4-ga cables, as shown in my earlier post (#50,
click here). That allows you to retain the original distribution block.
