Never heard of an "interference" type engine.  Most engines are phsically
capable of hitting the valves with the piston if piston hits top centre with
valve(s) wide open.  Usually, it's a crap shoot.  302 ford engines used to
be bad for timing sprockets.  They would often , but not always, bend valves
when the chain/sprockets failed.  Smal block chev's seldom did, but would
occassionally.  It really all depends on what happens at the failure.
Sometimes they'll slip a few cogs and the engine will quit running or run
poorly, no damage done.  Sometimes you'll be cruising along at 75 MPH, take
your foot off the pedal quickly and they'll sping 180 degrees out of sync
and valves and pistons will kiss.  Still doesn't mean the engine is toast.
Sometimes it's just pushrods that bend.  Other times it's valves.  Could be
all, could be all intakes or all exhaust.
Long and the short of all that, don't assume anything. If timing chain lets
go, pull the valve cover on one side, remove the rocker arms for at least
one cylinder.  Thread an adapter into the spark plug hole and apply
compressed air.  If it's holding, replace the chain and away you go.(check
for bent pushrods before putting them back).  If it doesn't hold air, you're
looking at valve job/replacement, which is still cheaper than a complete
engine.
FWIW
Steve