Joe, you, almost jubilantly, post: "it's functioning"
and Patrick show that while that may be so, there are serious problems I don't think it's a good idea to initalise your display in an interrupt routine. The same applies to calling the display routine from your ISR. My comment "I know it's not a good idea" and, I, honestly, believe that Patrick means the same, he is just not as 'brutal' as yours truly.

Joe, the fact that "it's functioning" does not mean that it is right.

Do not let yourself get suckered into believing that because it 'works' you are done. If you add anything serious to the main loop, what you have will fall apart. I can tell you, with some certainty, that if you increase the baudrate, your code will fail.

Now, you may say "I have no intention of adding anything serious to the main loop, or increasing the baudrate, so what is the beef?". If you do not develop good design practices with this (your first?) project before you move on, you may later find that you have developed some habits that will be almost impossible to get rid of. I am mainly refering to the "it works" instead of "it's right". Countless 'developers' have 'developed' something that 'worked' and been at a total loss when it stopped wqrking because something completely unrelated was added.

do implement KISS (Keep Isrs Short and Simple) before you move on.

Erik