I followed up on Brian's lead on that bloke in Ararat, 'Bondy' is his name and 'Brass Balls Motorcycles' is his business.
Had a great chat with Bondy and learn't a few more things about Jap fours. Bondy did not have 'the frame' (you know which one I mean Brian) in the shop, it is at home at the moment.
But he had an old Kawasaki custom chopper frame sitting there with a plunger rear end on it - an I am now thinking 'CB750 plunger frame custom build"...
Thanks for the tip-off Brian - Bondy says g'day and hopes you are out and about soon.