It has happened to me as well.
I bought a crashed 33 16v a long time ago so I could take the engine, gearbox and the rest of the stuff that were solid on it.
The car had been in an accident and the front end was smashed. The front piece of the shell of the car came and touched the crank pulley and the radiator was like omelet on the broken timing covers.
Although the timing belts were still on and the engine started, there was a tick tick sound. I thought it was the hydraulic tappets.
After taking the engine apart, I noticed that the timing was wrong. Probably jumped a few teeth on impact !
I took the heads off just in case. The pistons had hit marks on them from the valves , but they were neither bended or damaged
I rebuilt the engine but havent started it since. Its the one I have on my red sprint. I will probably get the chance to start it in a couple of months, but I'm confident that it will be fine