Preparing a photo for printing

I have had a print request for this photo after a client saw an old post on instagram- will be printed on acrylic or metal in likely 30x40 size. This was originally taken with 14mm ISO800 f/1.8 for 1.3s. I have since changed my approach and settings when I take aurora photos - much higher ISO and 0.25s or less exposure time for crisp details in the aurora itself since it is always moving.

But this is the photo the client saw and wants to buy, so trying to prepare it as well as possible. This is lightly processed with exposure increased slightly, highlights decreased, whites increased significantly, and shadows brightened up significantly to bring out more of landscape. No color changes or dehazing etc.

I have thought about getting some small sample prints on paper first to test the settings, but the issue is that the client is in USA and I am in Europe so it would take me some time to get samples from the pro lab that I will use for client in USA, and they would like this turned around relatively quickly.

Ideas or advice on any of this is very appreciated.