However I would need to know what the cm/Hg

It stands for centimetres of mercury pressure. This is required to tell you what pressure your carbs should be at tickover. e.g. The R1 is 22 cm/hg at 1100 rpm.
Here is the website of the Morgan Carbtune for those who are interested...
http://www.carbtune.com/index.html
PS - If your carbs are balanced to spec - does it mean that your fuel/air fixture is good as well? Just wondering...