Welcome to the mad house Phil.
I have jigged for the 68 360 Greeves chamber but it was put onto the backburner for some reason, I jigged another Greeves model too from memory but there was some doubt about which model it was so I never pushed it any further as Greeves would have to be one of the least asked for chambers.
The 68 360 has twin port headers into the one chamber.
Can't recall if I made a jig for the headers, I would have to look through my notes and jig pile.