Hi. Marcus Glenn have some B81 gaskets for sale
http://marcusglenn.com/b81-head-gasket?filter_name=B81
Give them a call, if the B81 is not suitable, the chances are they probably have the B80 one floating around.
Banister's is also worth a go.
http://www.milweb.net/go/banister/
I've dealt with both in the past and both Marcus Glenn and Banister's are helpful and friendly