"2 gauge" is smaller, less current capacity, than "0" or "1/0" (same thing) which are both smaller than "00" or "2/0".
Used "4/0" on an old crawler tractor with 6V system, that was likely plenty of overkill... Cable size depends on expected load and bigger is better until it just cost more money than necessary to do the job really well.
2/0 seems to be sufficiently oversized for a Stovebolt. Use welding or good quality battery cable for positive and negative, use the heavy bronze or copper tin plated battery terminal clamps/ends professionally crimped or soldered. (Never use the lead clamp on "repair" battery cable ends) Use heavy copper ring/lug terminals on the other end, crimped or soldered. Heat shrink with the glue/sealer inside at each end.
Braided ground strap as original from belhousing to frame is just fine, no real advantage to an insulated cable instead. Good idea to also ground cab to the engine or frame as others have said.
Grigg
