Bar Bet Winner!!

No, there were at least 2 different primary sizes and both had the same size secondaries. The base plate throttle blades may have been the same size (never measured them) but the primary venturi was necked down smaller in the smaller version. The secondaries don't open 100% on any of them, but close. Their designed that way because of the boosters. Same for TQ's. Their secondary throttle blades don't open 100% either.

I have only see the 650 and 725 versions so I'm not sure what was different on the 800's.

They are good carbs in spite of what some guys say. I ran a bunch of them on various GM's I had when I was a kid and had good luck with them. They have a small fuel bowl reserve and only 1 inlet so their limited on performance compared to a Holley but their still fine for most any street car under 500 hp and like you said they generally deliver good MPG