How about this Enoch
Gasket set
Worth a thought as you are likely to pay at least a tenner if they can be sourced sepperately
Buy the set .... Nick the exhaust gaskets & put the rest in your store as an almost complete set
Or Try this guy on Ebay
The Gasket shop
He has helped me find some really obscure stuff over the last few years
I beleive that the ehxaust manifold has two small gaskets, if all else fails, make a couple out of some thin copper sheet & smear a tiny bit of exhaust paste over either side.
Bolt the little devil up & that should at least top it blowing & would be better than now't