your rotor should be facing towards the frt of the motor but if you remove no.1 plug which is driver side frt and put your thumb or finger over the hole and bump the ignition when compression stroke comes up it should want to blow your finger off of it keep a eye on your timing tab or unless it is on the pass side of the timing cover you might need some extra help to watch line the line up with '0' tdc and that should put you in the ballpark your rotor button should be pointing to the front of the block now that is on a points or electric distributer not sure of a hei set up check on your hei instructions to see if it is any different if you try to start it and it wants to backfire or just plain goofy stuff your 180' out take dist out and turn the shaft the other way they try it again

 

p.s not exactly sure on this but i had a newer 318 around your yr in a 68 dart it had the lean burn system on it and the timing mark was on the pass side as with the tab on the timing cover i also had to swap the water pump from the original 273 that was in it in order to line up to the lower radiator hose i dont know for sure if the lean burn system had a different location for the timing mark or why it was on the pass side maybe doc could inlighten us on that matter