Timing valve train

[Toolman99]

I'm putting my timing chain set back on a 351w I know number one has to be at tdc does the top end have to be in a certain spot

 

[dave67fd]

If memory serves me...With the crank sprocket on and @TDC the crank sprocket mark should be straight up. Put the chain on the cam sprocket with the mark facing down. Keeping it in that position put the chain on the crank sprocket and then slide the cam sprocket on. The cam sprocket can only fit the cam one way with the dowel pin. Once correctly installed both marks should be facing each other.