I've tried over and over again trying to time my n/a vg30 in my 84 300zx.. I've got all the timing marks lined up but when I rotate the engine over twice it seems like the left head is 1 tooth before the dot while the right head and crank is dead on the dot.

The marks on the belt I know will.never be the same once rotated but I used those as a reference to set the timing along with the marks on the backing plate and crank gear. Car will turn over then slow/stop cranking

 

The dots on the backing plate never line up exact. Just count the notches in the belt and you should be able to get it.