mine has 3 holes for the thermostat housing and additional casting for a turbo damper, could this be a 500 item or is this just a later one

 

you can tell bey the water jacket on the exhaust side large one is early 2wd three holes is a late 2wd

If your head has a hole in the inlet face where the gasket goes about 5mm dia then its possible its a 500 head as these where for dowels and i think theres 2 holes

Out of all the 2wd heads the best to have imo is a late 2wd with the 3 hole water jacket

2wd early (not 3 dr) they have 2 thermo bolts



2wd late(note the area under the exhaust manifold is solid for better heat transfer)







Hope this helps a bit

Paul