I doubt that you harmed your aluminum parts heads since you didn't leave the vinegar in the block for a long period. Plus, since the heads are sealed against the block with gaskets , the vinegar would not have come in contact with the entire head surface - just the inside water passages. I did find this info.
http://www.roymech.co.uk/Useful_Tabl..._metals_1.html It does show that aluminum is not the best "container" for acetic acid. The chemical symbol for vinegar is CH3COOH and it is only 5% acetic acid with a PH of 2-3. Remember, we humans can consume vinegar without harm.
Yes, pure acetic acid will dissolve aluminum over a period of time, but since you are using only a 5% solution (vinegar) for a short period of time, I don't think you damaged your aluminum parts. Plus, your heads are not made of pure aluminum so the alloy metals may effect the corrosion rate. I am not a chemist or metallurgists and surmised this info from a computer search only. I use this stuff.
http://www.no-rosion.com/norosioncoolant.htm