Simple: How does the battery sit?

Hello, just bought a 1981 Kawasaki Kz305 csr a couple of days ago. Bike came without a battery, and I just invested in an overpriced one from an auto house. No issues with the battery itself other than it is a pain to wedge between the frame bars. And then when the battery is in, it doesn't sit right. So, long story short, do I have the wrong size battery, that it won't sit in the very bottom of the battery box, or am I suppose to have some stuffing/spacers beneath it to level it out? Can someone post a picture of how theirs sits or provide some guidance? It's a stupid question I know, but I've never had a battery box that has a step in it.
Thanks.

Welcome to the forum. Ok, here are some pics to your battery question.

Thanks for mentioning the exact model. A lot of guys don't do that.
Here are a couple of the Kawasaki diagrams for the 1981 KZ305-CSR from Partzilla.
You can click KZ305-A1 above the drawings for more diagrams.
Also, Yuasa lists the dimensions of the 305-CSR battery. I assume they're correct. see link below.

www.partzilla.com/catalog/kawasaki/motor...ittings-battery-case

www.partzilla.com/catalog/kawasaki/motor...electrical-equipment

www.yuasabatteries.com/battery/yb10l-a2/...ltd&vehicle_id=29181

Wife has a '82 KZ305 CSR Belt drive. Battery location is under the air cleaner. Have not had it out but does not look like there is anything odd about it.

I also have a Yamaha that uses the same battery. Definitely flat on the bottom.

Planning to pull the battery from the 305 for winter storage in a few weeks. I should be able to get a picture then.

The battery should easily fit into the battery box and sit firmly on the bottom.

Battery is a tight fit going past the frame, but sits flat on the bottom of the box. It is offset a little to the right of centerline. Don't think the air cleaner housing will fit, if the battery is not all the way down.