I don't think the part about "early" carbs having the one hole is a good way to say this. I have a 1975 R90/6, which is earlier, and it has 4 holes.
Some of the /5 carbs were the worst.
Serves me right for spouting off about my bike being such a great pleasure to start. I went out last night at Midnight for a soda and the bike wouldn't start right away...ugggh!