Pooch, they are Robertson head - nothing like phillips head, very easy to butcher up and you will NEVER get them out - suggest lots of penetrene, lots of patience & you make up a driver to put on a socket drive where you can get a bit of a turn on them - just a thought - do you really need to take them out ??
Square head is robertson, Straight head is straight, Cross head is phillips,,,,, Some one has replaced the correct one in the past 80 yrs... a tourer is on the track,,,
Australian A's had slot headed screws holding the windscreen pillars to the door pillar, they were not fitted with robertsons in this location, at least on the Australian made bodies. The Canadian bodies may have had robertsons in this location. The top of the slot head screws had a slight dome on them, they are not a normal slot head. If you need come original ones, contact me. davecana@(remove)yahoo.com