The ability to link a Gallery to a post instead of a page doesn't appear to be an option. Not sure why but I will leave that to the developers to sort out.
I have a portfolio page that I use the NG Pro List Album on and add in Albums containing the Galleries I want listed. I want the Galleries on the Portfolio page listing to link to a post and not a page (I have my reasons for this). In the Gallery settings you can select pages to link to but not posts.
After looking though multiple posts I found a way that works for me that is easy to implement without having to edit any files and I thought I would share it for anyone else that is looking for the same functionality.
-Install the plugin Speedy Page Redirect.
-This plugin adds a box to pages and post where you can enter another URL to redirect to on a temporary or permanent basis.
-Create your post you want to link to. In my case it is a blurb on the images with a feature image and I use the Masonry layout for the gallery.
-Create a dummy page with no content and in the Redirect dialog box from the Speedy Page Redirect plugin enter the URL of the post you created.
-Save the page.
-Edit your Gallery and select the dummy page you just created as the Link To page.
That is it. When the portfolio page loads it will be linked to the post and not the page. The Speedy Page Redirect plugin appears to set the dummy page up with a new permalink to the post so when the portfolio page loads, the link to the post is the actual link and not to the dummy page.
Thought I would share this if anyone else is looking to do this.