you would have to be very unlucky to have a chain fail(thats why its service life can be over 200k)
Tell that to 24v Cosworth owners
To tell if your engine is interference, remove the cylinder head, put no.1. piston to tdc, place 2mm of plastacine on the top of the piston, place cylinder head back on and replace bolts but leave them 5mm from tight, get a spanner that fist camshaft pulley(s) and cut it in half (this is important) - now turn camshaft through 360 deg - stop immediately if the head seems to lift slightly or it suddenly gets harder to turn, lift cylinder head and see if there are any marks on the plastacine - yes - interference, no - not interference.