Make your life easy. Assume 7-bit ASCII. No one needs all those other characters, anyway...
I think we should use a 4 bit encoding.
0 - NUL
1-7 - aeiouwy
8 - space
9-12 - rst
13-15 - modifiers
When modifier bits are set, the values of the next half-byte change to represent the rest of the alphabet, numbers, symbols, etc. depending on the bits set.