Morris Minor Owners Club

Most, if not all, Minor parts suppliers will be able to help. I purchased one from East Sussex Minors.
You will probably find that the existing is well corroded into the cyl cover and could prove a challenge to remove without damaging the threads, patience, care and perseverance are the key.
Good luck.

Also make sure you use the solid rather than concertina type when you do the job as they last much longer, and Bull Motif do hoses that are kelvar reinforced that should last even longer still