Need help how to find TDC/timing

[lasvegas69charg]

I need help from the motor gods.  I am rebuilding my first motor and I know I lined up the timing marks on the sprocket but I wanted to make sure.  I already installed the timing cover and dampener.  The top is still open with the heads, pushrods and rockers still exposed.  Is there a way to check that everything in sync and how do I determine tdc because the mark on the timing cover was off a little so I cant go by that. The main reason is not only to make sure it lines up on the sprockets but to install the oil pump drive shaft properly as the fsm states #1 at tdc and the slot in the shaft to be parallel with the cam. Worst case I will have to pull the dampener and cover off but it was a SOB to put that dampener on.  Thanks.

[Chryco Psycho]

 the best way is using a degree wheel & a piston stop in the spark plug hole you can  measure with a degree wheel how may degrees you are from TDC you are by rotating the engine clockwise fist & then counter clockwise , 1/2 way between is TDC
or you can get close by backing out the stop until the piston goes by but that will only get you within 4-5 *