There's a picture of the 'boat anchors' on ztherapy's website

http://www.ztherapy.com/ and press 'z car' in the left hand frame menu. Note the square mouths.

OK, I do see that these don't have the "Square mouth" that would be expected on "Flat Tops", but those float bowls don't look much like the ones on my Round Top SU's (though detail is poor in the pic). Would Flat-Top Suction chambers even fit on a earlier carb? It's been so long ago that I tossed the only Flat Tops I ever owned, but I thought that they were of much larger diameter than those on Round Tops. I need to look in my 73 FSM for a better pic or diagram of the carbs. Won't be until Weds that I can get to my shop.

Ah, the plot thickens.