Cheers for the sound advise twink it is identical to your one in the picture, apart from the green paint, and yes it has got an L on the block.
I think I have established that it is worth some good money, but I have decided to keep it in the car now following a lot advice from everyone, and being that it is a lot rarer then a lot of other engines out there.
Going to start stripping the car down soon for a full restoration, will post pics very soon.