Try Rare Spares for a wiring loom - they might be able to help you. If it's any help, our website has a copy of the FE/FC wiring diagram - check out
http://www.fefcholden.org.au/techinfo and follow the links.
There are a number of Smiths and Nasco branded heaters to suit FE and FC Holden, some images of these can be seen at:
http://www.fefcholden.org.au/techinfo/nasco/comforts But you will have to scour the swap-meets to find one, I would imagine. However, someone here might be able to help you.
Hope that helps,
RET