Customs Rochester 2GC, 2GE carburetor

Hello all
Any expert in these carburetors that can decipher the letters identifying vacuum ports ?. What are M, A, L, N, J, H as cast on the carburetor body intended for ?
Vacuum schematics are vehicle oriented and often do not tell the port 'letters'
From the point of view of the carburetor, is there a chart telling the use or function of such ports ? -Not the vacuum/hose diagram-
Also, is the 2GE model meaning 'E'lectric choke ?

This is about a Rochester 17058448 to be used on a 305 engine with no emissions equipment and want to know the bare basics on where to hook booster vacuum, distributor (ported or not), and what ports to leave unused, capped.

 

This is all I could find from the 2G carburetor stuff I had. Probably not what your looking for.
http://www.carburetion.com/r2.asp

 

maybe @carbking will jump in here. he is certainly our resident expert imho

 

Thanks for the vote of confidence, but carbking's experience, and library stop with the 1974 model year. This carb is newer. Have no information this new.

Would suggest looking in a factory shop manual. With that number, would guess 1978 Buick.

Jon.