Hello again,
Yes the guy is Mike (Shannon, I believe) he is based in Antrim and machines lots of parts himself, I bought some myself & was very pleased.
Not sure he is making the sprocket plate as such but you can contact him via his Ebay page here:
http://www.ebay.co.uk/sch/michael4317/m.html?ssPageName=STRK%3AMEFSXS%3AMESOI&_trksid=p2 053788.m1543.l2654