Cranking battery
Amp hours is not the consideration for a starting battery, cranking amperage is. Since you will not be deep cycling the starting battery (which will rapidly destroy it) you don't need an expensive deep cycling battery. I bought a 600 cranking amp "marine" starting battery a couple years ago at wal-mart for about $40 and it works fine on my 3GM30F. Should be fine for the 2 cylinder 2GM. I keep it charged up and only really use it as an emergency starting battery, using my 200 AH house bank for normal (including starting) electical chores.
