I've spent some time on this under the car and have decided that the open design with crossmember is my preference. After measuring and marking where a box would fit, I discovered just how tight access is once a box is dropped through the floor of the trunk. Access to the u-joint for the steering column would be all but impossible with the box in place.
Searching the internet, I found prefabbed battery tray brackets that are close enough to modify and make work.
Some trimming of the mounting flanges will be required but this bracket will fit. I'm thinking 4 bolts through the firewall with a backing plate possibly and a crossmember under the front edge of the tray like the later cars have. But, unlike the later cars this will all be removable if the need arises.
Could someone confirm some measurements for me on the later cars? Based on pictures I could find it looks like the width of the opening in the trunk floor of the later cars is ~12.5". And, the left edge of the opening is ~1-3/8" from the center of the hole for the brake booster hose. This opening would be larger than the battery with the excess open area on the right side. My thought is that copying this design would ease battery install and removal. I'm going to be installing a Wilwood clutch master cylinder with a flex line and banjo bolt as Doug pointed out to assist as well.
Steve
