Pistons hitting valves

[Brendan <bman@swva.net>]

I've heard and read about the concern of pistons hitting the valves when
the timing belt breaks (or when changing the belt, I suppose).  I was told
by a mechanic that the engine (or perhaps it's in the design of the heads?)
in my '87 5ksq was designed such that this was not a concern because the
valves didn't drop down far enough or the pistons rise high enough for them
to clash.  Can anyone confirm this, or is anyone aware of which (if any)
Audi engines were designed this way?

TIA,
B
'87 5ksq