To fit the box I use two B49-6 batteries wired in parallel (positive to positive, negative to negative). These machines don't need the extra capacity, but if you have the original box they fill the hole nicely. For many years I used a smaller battery with appropriately sized wooden blocks to fill the gaps. That worked well also. I really like the leather belt hold down you have, a practical solution to the problem. It almost looks original. You may already know that your machine is positive ground. More pictures are always welcome. Regards. Tom