Redline still stocks them with line references found is some Aussie magazines.
Lynx ones are available second hand, John Cain may have made some too. Speedway guys and Evil Bay is your option at the moment, unless you spend the money up front.
There were THREE types.
1. Iron head non cross flow 2V 250 head, 71 to 74 (XY/XA/XB). Commonly loved by Americans.
2. Iron head X-flow 1976 to 1980.5, this one has a water neck in its casting, (found in Cortina TE, Falcons XC, XD, Transit Van, F100 pick-up)
3. Then alloy head 1980.5 to 1993, these later ones have no water neck. (Cortina TF, Falcons XD 1/2, XE, XF, the Transit Van, F100 pick-up ).
Have fun!