Flexy has a running stocker in his shed.
Doubt youll find a modified engine for sale (I had one 4 years ago, you should have called then).
there's a guy in Adelaide that resleeves the alloy timing cover/water pump housings for AMC V8's, you could check him out as he's very well known in AMC street car circles, he may give you some clues.
Also check here:
http://australian.amcrc.com/
Otherwise, I know an engine builder who could do one for you. But whats the budget?