Smart move to use whole/cracked spices, the powdered ones are messy & cannot be removed without filtration. I get better results by putting my spices in a hop sack along with a couple of marbles to weigh it down, and suspend it in the carbouy with fishing line (sanitized of course).
I tried boiling caraway in water & adding that, but it was much more bland than I thought it would be. I used 1/4 as much in the hop[sack & got 10 times the caraway flavour.
All that being said, I'd start with 2 of each spice & go from there. Clove & allspice are going to be the strongest of the 3 spices & will likely dominate. You might want to increase the cinnamon, depending on the flavour profile you're shooting for.