BEGIN {
   my %muls = (
      K =>     1_000,
      M => 1_000_000,
   );

   sub canonize_units {
      my ($v) = @_;
      $v =~ s/^(.*)(.)/
         ( exists($muls{$2})
            ? $1 * $muls{$2}
            : "$1$2"
         )
      /e;
   }   
}

my @line1_fields = split, ' ', ...;
my @line2_fields = split, ' ', ...;

$line2_fields[5] = canonize_units($line2_fields[5]);

my @joined_fields = (
   @line1_fields,
   @line2_fields[ 4 .. $#line2_fields ],
);