If the timing chain break down...

[mr-reno-139]

Has it actually damaged valves I said the pushrods would bend which is clear from picture
The problem is you have gor a stepped piston only on 956 cleon
And my only experience was with larger flat topped pistons
As the engine has to come out now it is easy to remove head to double check
Please take photos of timing chain to see what's happened with cover off for repairs

 

[angel]

For tax reasons, I suppose, that's why it had been made in the first place.

 

[Leonardo.IT]

I think that also with flat topped pistons the valves could suffer for a chain failure, because the valves aren't perpendicular with the piston.
With stepped pistons the problem is worse.
The problem begun with the bolt on the camshaft that loosen up and made the gear moving until it broke the tooth on the camshaft itself.
I'll show some photos as soon as possible, I already made them.