But, you are right, the modules for BCD do exist, as you expected, however, they are not the easiest to find.

• Convert::IBM390 on CPAN seems to work with EBCDIC only
• Corion's PIC module is in Re: EBCDIC and COBOL records

Meanwhile, dbarkho14 probably has his problem solved, but here's my take on it, anyway:
(test data from Re^2: Perl Unpack Cobol Binary File and Fields)

use 5.011;
use warnings;
use Data::Dumper;

my $rec = "\0\0\1\257\a\344\0\3\0\0\0s\0\6\2\267\0\0\0\0\0\0\5E\35\0\0
+\0\0\0\0\0\0\f";
say "Length is ", length $rec;

my @fields = unpack "l>s>s>l>s>s>H18H18", $rec;
say Dumper @fields;

say Dumper map {
    my ($value, $sign) = unpack "A17A";
    $value = ( $sign =~ /[BD]/i ? -1 : +1 ) * $value;
} @fields[-2 .. -1];
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