The M16 is an interference engine so its possible that there could be a bit of valve damage.
Have you popped the cam cover off to check if the cams have broken? Not unheard of when a belt jumps
If they are ok, then it might be worth fitting the new belt and see if you can turn the engine over which would prove damage to the valves without whipping the head off - save the costs of a new head gasket set, bolts and a skim in a machine shop?
Arwyn
