The best way to test to see if your engine is timed correctly is to rotate the crank shaft through 720° of rotation then check your timing marks again. Since you (supposedly) have a non-interference motor, you will have no worries. If the marks line up again, then you're golden. You'll want to do this with a crank snout socket or put the harmonic balancer bolt back on to turn it. You don't want to use the starter. Make sure the spark plugs are out to ease the turning.
If you did have an interference motor, you can still do the same thing. The only difference is, if you feel any resistance at all STOP TURNING THE CRANK. That's why it's important to leave the spark plugs out, other wise you'd be feeling the compression resistance and not realize it if it were interference resistance. If you did feel resistance, you'd want to turn the crank backwards to the point where you started and then double check your timing marks. More than likely, though, you'd find they would match up to where they were supposed to be at that point.