Could you consider trying a 6510 instead of the 8501 in the C16? According to Wikipedia the 8501 is a variant of 6510 found in C64 and all chips are opcode compatible. Of course I can't guarantee that the 6510 wouldn't fry your C16, if you try it but it might be worth the shot.
The 7501/8501 variant of the 6510 was used in Commodore's C16, C116 and Plus/4 home computers, where its I/O port controlled not only the Datasette but also the CBM Bus interface. The 2 MHz-capable 8502 variant was used in the Commodore C128. All these CPUs are opcode compatible (including undocumented opcodes), except the 8502, where some differences concerning the undocumented opcodes have been reported[by whom?].
http://en.wikipedia.org/wiki/MOS_Technology_8501#Variants
EDIT: It seems that there's some differences. The 8501 is lacking NMI and has 8-bit I/O port instead of 6-bit in the 6510. Also there are pin differences.
http://ist.uwaterloo.ca/~schepers/MJK/7501.html
Perhaps an adapter could be made but you'd probably still be lacking the possibility to use a datassette.