I haven't mounted mine yet, but I'm planning to put it on the port side next to the transom seating. There's an area that's flat right before it slips up towards the arch. Looking at the marketing pics, this is where it's mounted at the factory.
Did you get the digital dash? My 270 only has two gauges but has an A65 chart plotter with digital gauges. Also one of the gauges on mine has a Smart Craft LED with additional info.