Obsidianspec wrote:I'd really rather not take the Dash out I've just finished stuffing around with the one I already have
ROTFFL
To put an H6 into and old H4 car you will need to change the engine harness.
To do that you have to take out most everything from the dash to the headlights and guards off the car.
The said harness runs behind the main HVAC box, so the HVAC needs to be unbolted and lifted out of the way by about 100mm to remove the old 4 banger harness and install the new harness capable of driving 6 injectors and variable camshafts. behind.
Suggest that you get a good Subaru Factory Service Manual and start your research.