Size prints/frames for headshot display

I am considering printing and framing a series of black and white head shots for a wall display. Exhibition Fiber paper I will be using, comes in 8.5x11, 13x19, and 17x22. These prints are not intended to fit the 8x10 size required for some types of headshots, but rather to showcase the work. The headshots are just that. head and shoulders. I have a rotatrim paper cutter so cutting down say a 13x19 is easily doable. I am also flexible on the print size as I cut my own mats, so some square, could be done. However, I wonder if a consistent size, a mat and frame throughout the display is more desirable. Any suggestions? I am looking for a gallery type display. And would like to be able to drop the matted work into a standard frame size.

These folks have some interesting slip in options. They have an assortment in t3x19.

Snap Frames | Front Loading Aluminum Poster Holders

I have a portrait set for the local theatre to do - shoot Thursday. Last year I did 8x10, this time I'm going to stick to the 4x6 aspect and use 8x12. I'm going to fool around with the printer a bit and center on 13x19 stock. No cutting and a nice border.

Sandy, do these frames accept a mat?

Yes.