I just got a No. 4 Mk. 1 from J&G the other day. I was very excited because externally it appeared to be in very serviceable shape. However, the barrel is completely hashed. While trying to decide if it was worth trying to rebarrel I searched gunbroker.com for Enfields and saw quite a few, including some Long Branch ones. Of course you always take your chances on a used 60+ year old gun. Good Luck.
Jer..