Here's mine.
Get some pictures of the guages you intend to use or different ones you are considering. Scale them up to the right size using photoshop or whatever and print them out and glue them to some card board. Cut them out and stick them on with blue-tac in different layouts till you find one you are happy with. That way you can try the layout from the drivers seat and see how it looks before cutting holes in your dash.
Cheers