The 30 inches in front of the nose datum is the Manufacturer's Datum Point (MDP). This was known as Station 0 and all the other references are from this point. The Trim Datum was at FS 527. This was the datum used for weight and balance purposes.
Whilst looking for something else this came to light.
It shows the ORIGINAL 'K' trim envelope with restriction imposed when fuel was in the externals. It does not show the forward and aft airdrop extensions.
So you can see that the MAC is 164.5 inches (all in 'old' money !) long and Lemac is 487.4 inches aft of the MDP. Cof G runs from 15 to 30 percent of the MAC but is also a function of the a/c weight.
I think that is quite enough for now ! My brain hurts.