I just went out and looked at one of my '82 LS's, the battery is 77 mm wide and there is a 2-3 mm gap between the battery and the bottom flange of the battery box .
I think an 80 mm wide battery would be really close, if it doesn't fit, you can reuse the piece of wood, you'lll replace the battery down the line anyway .
The top cover, don't know, mine crumbled from the heat here decades ago !!!

Currently 99 F, 37 C at 1450 .