1974 D300 360 fresh rebuild will not start

If oil does not increase compression, the valves may be open at wrong time or "just open." This nonsense of cam timing is stupid. Check them with a straightedge at the very least or learn to degree them. And you cam time them EITHER at "6 and 12" or at "12 and 12". When you rotate the crank one turn, the marks will be the opposite location of where they were at first.