single carb
I went through this carb business this year. Got a mk 2 amal and a manifold kit. The bike runs well now, starts first time and I am happy with it. The downsides were the carb quality, poor straight out of the box (spanish made Amal) but the suppliers were very helpful (RGM) even if my patience and ability were stretched! I did speak to other specialists who put me off the mikuni idea as they are very expensive and, I am told, the UK doesn't have a great supply of them.
If i were doing it again i would go for a Mk 1 as they are so easy to work on, and you have 2 already!
This site has the answers, there were replies warning of the poor quality, but as with most things, if you ask ten people there pinion, you get eleven answers so it's down to personal choice, who and where you can get spares from and the the big one for me, who gives you the best backup and support.