I'd suggest either installing g77 if you can or changing the make file so that the line which reads something like "F77 = g77" is instead "F77 = gfortran" or whatever version of fortran compiler you have on your system and see if that works.

if you are truly having to convert Fortran programs to C, then you need to make sure that 'f2c' is installed. f2c translates Fortran as input and generates C as output.