Go to HondaChopper.com for a carb spec list. 7A's are listed as 69K and 75F if I remember correctly. These carbs would have bowls with clips on them rather than screws like the 77 & 78 have. The Honda Keihins are 28mm.
As far as Mikunis goes, guess if you have smoothbore 29mm carbs I'd probably stick with those.