Engine Building Begins: Need your input

[almcbri]

Engine: stock 93 GM 5.7L 350 TBI from a Caddilac with 10K miles

Holley ProJection 670cfm TBI
TBI Adapter Plate
Edelbrock Performer Aluminum 4 Barrel Intake Manifold
Heads:Stock
Stock Wiring Harness
Computer Stock
Coated Headers 2.5" Collectors
Exhaust Dual X pipe 2.5"
Aeromotive Fuel Pump kit
Cam Shaft:??
Distributor:??
Water Pump:??
Any other changes or additions?

I am wanting a very mild engine. 350 HP is what I hope for. I don't know whether that is possible with the direction I am going? I would greatly appreciate your thoughts and suggestions in order to reach my goals. I am not a engine guy.
Here is my list of importance:
-Reliability**
-Power (350 HP)
-Fuel Economy (15-22 MPG)
-Cost