That is a MK2 concentric which are much the same as a Mikuni. They came out in the late 70's. What period are you riding your Greeves in?. I think that Amal will be OK for pre 78, im not sure on the exact date they came out but it was around then, but they would not be ok pre 75. Having just said that, i think carbies are open slather actually apart from flat slides so you probably could use it in any era but it would not be in the right spirit to use it on older bikes before the MK2's came out. They were typically found on late 70's to mid 80's Triumph twins.
Also a BIG problem on the MK2's is the choke plunger. Dont bother using the one in there. The rubber will be hard and compressed and wont seal if its still the original which is likely. I have to replace them on lots of bikes with MK2's and is usually the first thing i do and also fit a complete new gasket/seal kit through the carby. You can buy the complete brass plunger with the rubber in it but they are sometimes difficult to find. If you cant get one you can pick out the rubber and punch out a little rubber disc from some Viton rubber sheet and press it in and it will fix it. It makes a world of difference. Also the slides can wear pretty bad too. Even though they were better than the MK1 concentrics, they are still not as good as Mikuni slides and i have had to replace a few MK2 slides before.
