Ooops, that's what I get for reading posts while in a hurry to get to school, I kinda got your reply mixed up. My bad...
Actually, thanks to a link posted in another thread here I found a Pdf version of the parts list for this bike that someone here had made available. From that I just got confirmation that the carb code should indeed be 064A for my bike! Happy happy, joy joy!! I do plan to put the stock airbox back on. The carbs are vacuum balanced (Thanks to a garage friend that's a sertified MC mechanic and has worked at a Honda garage. He has a superb looking CBX by the way..) I do think that the carbs could do with a rebuild kit (There's a couple of gaskets missing anyway...) I also suspect that one of the carbs run a bit leaner than the other as one of the header tubes are "bluer" than the others. Thanks again TwoTired!
I did suspect that the front end could be from a K, as it didn't look quite like the F pictures I found on the internet. Oh well, it's there, and it works....