If chain breaks, will valves break too? Thanks.

 

Usually YES. Also possibly pistons depending on speed (revs)

 

+1

However, reports of chains breaking seem to be close to zero on the 4.2. Avoid the 4.0 unless you're going to upgrade the known-inadequate parts.

 

I have seen 4.0 litre engines that break the upper chain and escape having damage to the inlet valves. Once new chains and tensioners were installed, the engines started and ran normally, while others have not been as lucky.

To directly answer your question, the V8 engines are interference design.