The correct way would be to observe the valves on the #1 cylinder. Or find the timing mark on the balancer. The problem with the balancer mark is that the LT1 NEVER had a slot/keyway in the hub to keep it from moving so this MAY NOT be the most accurate. I would pull the driver side valve cover off and rotate the engine by hand. Turn the engine over until you see the number one cylinder exhaust valve rocker arm JUST START to move from the closed position to open. You may need to turn the motor over a couple of times to reach this point, but do not turn any further. This should be TDC.
Please dont take this the wrong way, but grab a book from autozone this will help you out. The HAYNES manual is NOT the best but it does have lots of useful information. Also the internet is the greatest resource, you could probably find something by google if you needed more. GOOD LUCK!