All 1960 2 door Impalas would be hardtops. The other less expensive styles would be 2 door sedans. Hardtops have no door posts between the front and back windows giving the "all open" look. Sedans have door posts.
Any "W" motor will be a valuable find compared to a SBC as even the original six is turning more heads these days. There have been so many cars "upgraded" to a small block V-8 that no one looks anymore unless it is blown motor or an LS-x motor.