How much vertical travel should I expect for a solid axel (Moser 8.8)?

I am using the complete kit stock Koni shocks with 350# springs.

I was so happy my pinion angle was within limits right from the start with no adjustments that I neglected to look at my battery box and differential housing clearance. It was my muffler guy who asked me what I was going to do about the clearance! As you can see sitting at ride height, the two just make contact with each other with no room for upward movement. Well my best (cheapest) solution considering I already bought the battery and the FF Metal battery box is to cut and shorten the bottom of the battery box. I was thinking 1.5 inches should clear it? Would 1.5 inches be enough? I could live with the battery taking up space sitting above the floor of the trunk. And with 1.5 inches higher on top by the posts, I would not need to make adjustments for the battery cables. If I need to go over 1.5 inches by the battery posts I might need to reroute the battery cables and/or re-run longer battery cables $$$. Of course I would make a shroud to protect the battery posts from above. My last option is to look at the original cover to see if it would clear. However, that would involve draining the oil, taking the cover off, etc. What do you experts think?