So glad you have found the thread interesting Dave. I think you may have a job to get hold of a reversing ring for that size but you could do what I did. I have a p system 58mm adapter. I duck taped an old 50mm lens to the adapter it doesn't look very tidy as I had just taken the duck tape off and stuck it back to take photo.
Adapters are £3.99 from this firm for the 77mm ones
http://www.virtualvillage.co.uk/item...edium=shopping