Advice Needed - Can't Start Rebuilt 273

Longgone is thinking you have hydraulic lifters? Not sure if I understand him. Anyway, Rotate the engine by hand and check the gaps on the valves. Sometimes they are on the ramps when you think they are on the base circle. Adjusting them "by the chart every 90 degrees" has never worked for me. Spark plugs should be N10Y or equivalent for high performance.