I am not a PS user but I know you can rotate items in PS and place them down. You may have to get them into a selection or put them onto their own layer but it can do it ok. There are loads of top down stuff in the resources section of the forum and links to other places where you can find more. Generally the Dundjinni forums have a lot but the largest collection of them is offline for a while until people can work out the download for them again. But we all post top down stuff all the time.

BTW: your map is great ! Well done.