Found my original 73 head today.
Measured the intake spigots.. they seem larger than the earlier ones I measured a while back.
These measured about 34mm od not counting the lip.
Last one I measured was 32mm od, which made me wonder how you could port them to 31mm..
Also the 34mm type was tapered on the id.. from 29mm to about 27.5 or 28mm about 3/4 of the way in.
I will try to drag a 72 head out it looks like they have a bit of difference..
