10 sec. 318?

If it's a "work in progress", I'd put a cam and headers on the 'teen and concentrate on the rest of the car. Chassis, tires, brakes, fuel system, rear, gearing, tranny, weight loss... Then worry about the engine. You can get a season or two of experience and debugging with an easy, no maintenance engine. Then build something stronger when the foundation's good. To build a safe 10.50s car from a basic stock non-performacne vehicle will cost upwards to $20K doing a lot of the work yourself, and assuming it needs no body work. A 12.90s A body costs about $6K starting with the same vehicle and with the same assumptions.