Masonry Grid Portfolio image size issue

I am creating a portfolio for an artist. She wants all the thumbnails to be Not Cropped. She would also like all the painting thumbnails to be in proportion to one another, meaning looking at the thumbnails would look a little like seeing the paintings on a wall in a gallery.

I am using the Masonry grid, but I have two issues:

1 – Thumbnails do not represent proper proportion. Very tall paintings look too long, while wide paintings get compressed into whatever size column I’m using. At the moment I’m using a three column layout because the difference between tall and wide does not look as disproportional.

2 – The very tall paintings do not fit into their “frames” – meaning the box that holds the caption is too wide for the very tall paintings – or the painting is not filling up the full width of the column for some reason. See the painting titled: “Monarch Code” near the top of the page as an example.

http://2c1.f0b.myftpupload.com/paintings/

It seems that all the other ways to display art with thumbnails and a light box always crops the painting’s thumbnails. Is there any way to get a grid with non-cropped thumbnails, even without the Masonry grid – more like an old fashioned Table layout, but where I don’t have to custom make all the thumbnails beforehand?

Thanks for your help, and once again, THANKS FOR MAKING SUCH A WONDERFUL THEME!