We already have a specialized type for int (actually an enumeration);
typedef struct {
    Py_ssize_t size;
    void *elements[1];
} asdl_seq;

typedef struct {
    Py_ssize_t size;
    int elements[1];
} asdl_int_seq;

Why not just include these in the Python-ast.h and auto-generate them in the asdl_c.py