Battery Covers

Has anyone ever gotten the battery covers that have the fake fill caps?

I don't want to get an original battery, so I feel as those these covers are a good alternative.
Has anyone used them, and how do you know how many caps there should be, and the color of the caps? And has there ever been an issue with the covers preventing the battery from properly venting?

This would go on a 67 GTX.

I can't find any group 27 battery toppers.

I went to a few stores today to get a new battery, but the ones I found either had strap extensions on the side that would require dremeling, or one where the posts sat below the vents.

Gut your old one