You can make good power with a well built 396. 781 heads work well on most mild street big blocks. If you're looking for a good, solid running street engine use Edelbrock's Performer RPM manifold/cam package but use the Airgap intake. Speedpro makes a .100 domed piston for a resonable price. I used this setup on a 402 with a 750 Holley in a 66 Malibu and it ran really strong for not a ton of $$$.