I did mine, unlike others I have seen I cut the top off to be used as a lid. This also left the whole case intact.
I treadled the post and screwed the post in but may just bolt a cable to them and then onto the new battery inside.
I also epoxied some plastic angle {like angle iron} to hold the top in place but the factory hole down would work. I kinda go past what is needed at times.
I polished the rubber case as seen in the picture with Yellow Caps. And have 2 sets of caps in case I want the 24 to look like a 27 I kinda go past what is needed at times.