I wouldn't want to use an E head for two reasons: 1) with 10.5:1 CR, it can be a challenge to tune them for 92-octane normally aspirated, let alone with boost, and 2) the exhaust ports don't flow as well as on the carb heads. With forced induction, the slightly larger intake valves on the EFI heads will do nothing much for you, while exhaust flow restrictions will cause you to hit a wall where more boost doesn't increase power.

If detonation is avoided, stock pistons are good for low boost levels. The B21 pistons are no stronger (head gaskets are available). You want to go to forged pistons for higher boost.

The C cam is a reasonable choice. You don't want a cam with much overlap, or the boost will blow the intake charge right out the exhaust ports.

I can't think of anything functionally wrong with the EFI intake manifold, except that it's big and doesn't leave much room for a supercharger.