If you add 2 more rows and make it a 5x7 display, I've got a set of lookup tables already made up for the complete ASCII character set, should plug right into what you've got going.
Originally, I used the character tables for a 122x32 graphic LCD, and now I'm using it on a 130x130 4K color Nokia knockoff LCD (in addition to a 16x2 LCD, all at the same time!).
I'll post them here when I get a chance...