Ok, here is some info and a copy of what the person doing these engines sent me about parts used in the rebuilding of these Listers.
"The answer is this. All the parts are genuine Lister, wherever possible. Some parts, such as castings, are no longer available but I have a stock of most of these. Other castings, such as cylinders, would have to come from India, it's the only place left. The SOM parts are not actually available in India!
Contrary to popular belief, Lister didn't make all the parts for their units themselves. Fortunately some of their UK suppliers are still in business and I'm able to buy batches from them. Some parts I have to have specially made in the UK and France. Others, including gaskets, come from the far east, but they are good regular quality."
He also informed me that regulations apply to engines manufactured after 1986, so these that he does are good to go. He includes paperwork to prove it also.
Derek