I have a loaded 2003 Coastal 270. The AC is mounted on the port side of the aft cabin. There is an access hatch to that space, and a grill is mounted on it through the bulkhead.
I can take pictures if needed.
Any other questions, I'd be glad to answer.
NOW, I need YOUR help.
What year is your 270? I need a picture of the convertible helm cushion so I can try to have one made or find one for my 270. If yours is a 2000-2003, it should look the same. If you're able to take some pics, I would like a picture of the cushion in both positions, as well as all the sides and bottom.
I hope that helped.