Hello again fellas
 
Im replacing the old carby on the datto (has 1200 motor) after it lunched itself and filled the intake manifold full off petrol.
 
http://www.ebay.com.au/itm/321088171643?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
 
This is the carb im using. Thre engine has the following mods:

•  "Big" cam out of a A14 engine, dont know exact specs.
  
• extractors
  
• Milled head
  

Would these mods warant a jetting change? I would imagine it would even if very minor.
I'm new to these carbys and was wondering if anyone could give me a jet size starting point for the main,idle etc..
 
Also, i was wondering if the cam would be causing a very low to no vacum situation during idling. As my vacum advance isnt working and the motor is set a 10* advance permanently making it crap off idle then nice then crap up top. I was thinking if this could possibly be rectified by putting a lighter diaphram return spring into it?
 
Thanks for your time guys.