1974 D300 360 fresh rebuild will not start

Just to sum up; your timing chain sprockets are incorrectly timed. Slide them off and install them with the crank sprocket pointed up [12 0'clock] and the CAM sprocket pointed down. Check with a straight edge using the center of the cam hole and the center of the crank [eyeball it]. The marks should line up. Assemble. Note the harmonic balancer timing mark. It should be on zero.

Cyl. #1 on compression stroke, dist. shaft gear slot pointed to left front intake manifold bolt, dist. rotor pointed to front of car [#1 spark plug]. Add oil and fire it.