I have a 71 454 425HP stock motor, and wanted to know what kind of HP I could get out of a set of aluminum heads.I was looking at a set of edelbrock performer heads rectangular port and a air gap manifold, or if someone has another choice. Thanks luke

Heads (http://users.erols.com/srweiss/tablehdc.htm#BBChevy)

Thank you so much for that link.