When the distribution strap was broken, it is possible that the cylinder head be fined or bent.
Doing things right, when a thing of this type happens, what is done in the workshop is to take the cylinder head to check and rectify seat plan, valve seats, guides, mount new valves, and of course mount all the joints of the upper part of the new engine especially butt joint.
If you try to save one of these steps, you run the risk of setting up a damaged butt without knowing and causing damages to the client that pays you for your work.
Another issue that can bring you by the head is that when they hit valves against pistons, nothing happens, but sometimes and depending on the violence of the blow, the piston's head is crazy or the connecting rod is folded. (It has to be a tremendous blow, but it is not the first time although I don't think it's your case)
greetings.