Did you put a new harmonic balancer on the engine? or did you reuse the old one?
If you used the old one, it is quite possible the outer ring that holds the timing index mark has slipped out of position...
What about the timing tab...which one did you use?
Same thing for the starter...if you reused the old one, it could be worn out....
Battery cables...again...did you reuse the old ones or put in new cables?
Are the chassis to engine and cab grounds in good condition?
Vacuum to the distributor should be ported vacuum...not direct to the manifold....there are two sources for vacuum on a carb...one that has no vacuum at idle, meant for the distributor...so it should show zero vacuum at idle...(650 rpm)
and one or more that are full continuous vacuum for various accessories.
