Where do I find the crankshaft TDC timing mark?

There isn't one. You set TDC with a pin (available as part of a Draper kit). Once you have set the mark on the injection pump sprocket aligned with the mark on the cover/head you have no. 1 cylinder on compression, then screw in pin and carefully turn crankshaft clockwise (looking at engine from timing belt end) until it locks against pin.
email me at samson@dsl.pipex.com if you wish.

Dave Oliver
July 2006