It's time to say goodbye Steve, the sad facts are no one will want an 1800 that has almost certainly given the rundown of what has been done to it, been cooked
Take off the new arm to sell on and have the rest uplifted by a scrapman with a HIAB, then move on with life.
I'm going to do something similar with the ZT, which at the moment has more than 12 months MOT, but at some point they become not worth repairing.
All the best
Brian