Inspired by kennethk's second approach above, this avoids the reversible complexity of either  '(B8)*' or  '(b7)*' in favor of  'C*' simplicity:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $out;
 $out .= sprintf '%07b', $_ for unpack 'C*', '4B3A';
 print qq{'$out'};
"
'0110100100001001100111000001'
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