There's a thread explaning the "extra" characters available here. Generally speaking, you should be able to just plug in the score_graphics.asm file I posted for Deimos Lander. It will reduce your available space by a few bytes, but otherwise it shouldn't have any real effect on your code. You can either look at the Deimos Lander code for an example of how to eliminate numbers (specifically, look at the Level Display) or you can wait until I get a chance to patch your code.
BTW, if you're looking for more programs, might I suggest finishing the calculator?
Almost done, I have one last question, though. It seems with this...
dim blank = score+1
....I am only able to "mask" every other sprite by adding 1. How would I mask the others? Half numbers?