I put mine in the same spot as the Turbo Coupe, in the kick panel area of the passenger side. It is relatively accessible (if need be) and the harness is pretty much "length-ed" for that location. Images include the LA-3 ECU location and the firewall breakthrough points using the T/C grommets.
I never got around to completing the cover..., but I bent (with heat) two 90 degree bends in the stock cover to get around the computer. With the (now) shorten end I was going to cut a second panel and lengthen it with an overlap section and a few small pop rivets.