Can a 305 Chevy motor fit in 87 astro van?

No, a 305 Chevy engine will not fit in a 1987 Astro van without significant modifications. The Astro van's engine bay is relatively compact, and the 305, while not enormous, is still larger than the stock engines typically found in those vans (usually a smaller V6). You would encounter substantial issues with:

* Clearance: The engine block, intake manifold, and accessories (alternator, power steering pump, etc.) would likely interfere with the firewall, inner fenders, and other components within the engine bay.

* Exhaust System: Routing the exhaust system would be a major challenge.

* Transmission: Matching the transmission to the 305 would require modifications, potentially including custom mounts.

* Mounting: Creating custom engine mounts would be necessary.

While some people undertake incredibly ambitious engine swaps, fitting a 305 into an Astro van without extensive fabrication and engineering is highly impractical. It's far more feasible to consider a smaller V6 swap or rebuilding the original engine.