I would try contacting
www.mamod-steam-railway.co.uk , i am pretty sure they will have someting for you. The port faces are not listed on the website but they may well have some on stock that have been removed from a modified one, they seem nice to deal with in my experience.
Wonderful little toys, and a real art to keep on the track with their self adjusting regulator and 0 to 60 in about a quarter of a second lol.
Ryan