Need Help to Repair C++ Mac OS X Program after 64 bit Conversion.

FinancesOSX is a program I wrote 10+ years ago in C++ for Macintosh. It broke when I attempted to recompile for 64 bit. There is a preprocessor error that the <Cocoa/Cocoa.h> file was not found, and a runtime error that it was unable to find the file <MacOSX 10.5.sdk>. 

Does anyone here have the skill and time to help me fix these problems?