You have to turn the battery sideways and get a special tray. Rustys Off-Road sells battery trays that are made for 2 Optimas. Here's one in a 5.4 Expy
I am running a stock battery with disconnect and a deep cycle backup for self jumping and extra juice when needed.
I have them diconnected now as I am pulling the motor this weekend. I will post some up when I get her back in. Sorry shoulda prolly took some on the install. I am not good at doing that. LOL I get in a hurry to get the project done and forget about pics.