Firewall section could be improved with some additional holes and some of the factory locations for certain items for fitment like the heater/defrost assembly. It is hard to explain without your company actually having possession of the heating unit duct work and other various components that attach to the firewall from inside. One of the hardest things to do was to locate and drill the 3 mounting holes for the heating/defrost unit to the Repli-Tub firewall (Repli-Tub is what we refer to your units that come from the Philippines here on the Jeep Forum).
One of the first problems I had was fitting the heater fan motor through the hole that is already in place by your company. Because the top cowl section opening for the fresh air duct was not on centerline, off by a 1/4" from center, it forced me to convert to a popular upgrade of a larger fan motor. The hole is correct size and location but mounting the duct work on the upper plenum forced the assembly towards the passenger side by a 1/4". Therefore, a larger hole had to made slightly off center from existing hole.
There is also a bump or dimple in the OEM Jeep tub that allows a shaft from the duct work to clear the firewall after the heating/defrost unit is installed. I had to grind the end of the shaft in order for it to not make contact with the Repli-Tubs firewall once installed.
The throttle hole is missing and it is angled and a square hole. I drilled the hole in the factory location and then filed the corners to make square.
Once the square hole was made, I used a carriage bolt fitted with washers bolted in the hole and then carefully heated the sheet metal around to bend it to the proper angle.
It would be nice if the two strut brace brackets attached to the firewall upper section were in place. These are needed to provide additional support for the front grill.
A larger square hole opening is needed for the engine compartment electrical bulkhead connection to pass through on later model CJ's and YJ's.
There's no hole for the washer fluid hose or a hole for the nozzle on the top cowl section. Maybe not to important in states were it does not rain so much.
No battery tray mounting holes. 3ea. needed.
No bracket for the E brake assembly or Parking Brake.
No threaded backing plate for the Battery Tray.
Some more OEM factory Firewall Photos: