Will a 1970s Chevy 350 intake manifold fit on 1980s 305?

No, a 1970s Chevy 350 intake manifold will not fit on a 1980s 305 engine. The bolt patterns and port shapes are different between the two engines, so the intake manifold from the 350 will not bolt up to the 305. Additionally, the 305 has a smaller displacement than the 350, so the intake manifold from the 350 will not be able to provide the correct amount of airflow for the 305.