I am pretty sure I have the pattern somewhere for this middle cross member casting. It is possibly the only pattern in existence now for this part, hence why possibly nobody is currently able to offer these. I have the N type one also.
You are welcome to borrow it if it helps. Iron foundry work around the Leeds area at the moment is proving problematic. The best foundry I used for 15 years shut down last year and the new one has been sat on some of my casting work now for over 3 months.