i bought a new battery the other day, a exide 12 volt battery, exactly same dimensions as the original battery, but the poles are on the other side and the lugs are different. Ill take pictures of my "custom" installation in a upcoming post.
You'll need a Negative Cable adapter for the new battery as well. The OEM 12V battery has a tiny pole.....
i have a new positive pole( i had it laying around ) , but the negative pole i ended up stretching the original and drilling a new hole and putting a brass screw through with a nut