It just means the intake is cast as one piece with the cyl head. For a stock engine it is fine. Running other than the stock carb requires using a non intergral head off of any 230 - 250 - 292 so you can use a separate intake for the carb or carbs. Some have made adapters to use a larger carb on the intergral but overall it is still very limited for performance gains. The other difference is the valve cover is not intechangeable from intergral to non intergral heads.
