Ya gotta love all that stuff under the floorboards like the battery and the master cylinder. I installed an MC on the firewall but decided to leave the battery under the floorboard, making my carpet semi-removable to get at the battery. The right side of the 54/55.1 firewall isn't exactly clean to locate a battery due to interference with heater hoses and the heater unit itself. But if you can find a location, you might want to look at the battery pan from a 1955 chev passenger car. The battery is located on the right side of the firewall and the pan (available as an aftermarket part from places like CCI) should be a relatively easy bolt-in.