As far as I can tell SDCC support for 16F chips is not good. There is APP-II's PIC16F873 but I do not know much about it. I suggest you move up to the 18F family (if you can get them) and use MCC18. If maybe not start a import company and sell them?
This **broken link removed** says this about the PIC 16F and 18F in regards to C compilers.
The 18F architecture sucks, but the 16F architecture sucks many orders of magnitude worse