Updates:
First off, I got the battery installed. The connections were on the opposite side of what I needed so I purchased some aluminum (do NOT buy steel for something like this - it will rust) from a local hardware store and cut them to length. The finished look is this:
And here is where that big 0 awg ground goes to:
I then covered the dual runs of 4 awg and had to modify the fuse holder to accept the twin ring terminals. I didn't want to show the company of the fuse holder (SoundQuest) so I mounted it inverted:
