I always make my "pin" hole too large to allow for adjustment on either end. the pin hole is not to support the boom, but to prevent it from sliding out if a clamp bolt fails, or you forget to tighten them. meaning, it doesn't have to be perfect. it only needs to be through the boom, and not allow it to slide out if there is a failure.
do as others above have mentioned, and elongate your hole, or twist the boom and go at it again.