Script to compare two directories and copy files missing from A to B

I am in need of a script to run on IBM AIX v4.3.3 to compare a directory that contains nearly 60,000 files to a partial copy of the same to determine which files are missing and copy the missing files to the destination. I have done some searching on the web and came up with nothing that I have not thought of already. DIFF is no good because it wants to compare the files. This is not what we are interested in resolving. We only want missing files to be copied to the destination directory from the original source. I found one script that was close called 'cmptree' but cannot figure out how to take its results to the next level to initiate and complete the file copy. The cmptree script is as follows:

#!/bin/bash
#
# cmptree: compare directory trees recursively and report the differences.
# Author: Ives Aerts

function gettype () {
  if [ -L $1 ]; then
    echo "softlink"
  elif [ -f $1 ]; then
    echo "file"
  elif [ -d $1 ]; then
    echo "directory"
  else
    echo "unknown"
  fi
}

function exists () {
  if [ -e $1 -o -L $1 ]; then
    return 0;
  else
    echo "$1 does not exist."
    return 1;
  fi
}

function comparefile () {
  cmp -s $1 $2
  if [ $? -gt 0 ]; then
    echo "$1 different from $2"
#  else
#    echo "$1 same as $2"
  fi
  return
}

function comparedirectory () {
  local result=0
  for i in `(ls -A $1 && ls -A $2) | sort | uniq`; do
    compare $1/$i $2/$i || result=1
  done
  return $result
}

function comparesoftlink () {
  local dest1=`ls -l $1 | awk '{ print $11 }'`
  local dest2=`ls -l $2 | awk '{ print $11 }'`

  if [ $dest1 = $dest2 ]; then
    return 0
  else
    echo "different link targets $1 -> $dest1, $2 -> $dest2"
    return 1
  fi
}

# compare a file, directory, or softlink
function compare () {
  (exists $1 && exists $2) || return 1;

  local type1=$(gettype $1)
  local type2=$(gettype $2)

  if [ $type1 = $type2 ]; then
    case $type1 in
      file)
        comparefile $1 $2
        ;;
      directory)
        comparedirectory $1 $2
        ;;
      softlink)
        comparesoftlink $1 $2
        ;;
      *)
        echo "$1 of unknown type"
        false
        ;;
    esac
  else
    echo "type mismatch: $type1 ($1) and $type2 ($2)."
    false
  fi

  return
}

if [ 2 -ne $# ]; then
cat << EOU
Usage: $0 dir1 dir2
Compare directory trees:
  files are binary compared (cmp)
  directories are checked for identical content
  soft links are checked for identical targets
EOU
  exit 10
fi

compare $1 $2
exit $?