The good news is, all you need is a set of Vortec heads for about $500 bucks and a more modern cam to more than double your horsepower. Those heads you have are low performance, low compression heads and basically they suck.
If you do go the Vortec route, then I would recommend the Edelbrock RPM Air Gap Vortec manifold for max power. Or if you want the heat risers functional, then get the Performer RPM without the air gap feature. Power is only incrementally lower than the air gap.
