Stock 72 318 power gains

Hey everyone I am waist deep in a base 72 duster restoration/mod and was wondering just about how much power I may be adding with all of the motor upgrades I have sitting on my shelf. its a base 72 318 which was rated at 150 horse and 260 ftlbs of torque with stock manifolds and 2bbl carb and single exhaust.

I have a dual exhaust setup with flowmaster 50 series waiting. was going to port the factory exhaust manifolds. I have an aluminum air gap intake and an edelbrock 600 cfm carb. I also have a comp cam kit with cam at 260 duration and .440/.440 lift. was also planning on porting and polishing the original heads.

I am looking to get as close to 300 horse as possible does all this get me close? I know its difficult with the 8.6 to 1 compression

Yur in trouble. Lower your expectations.
You didn't mention why you wanted 300hp; that's the first hiccup. And the second is Normally aspirated, lol.

Forget all that; Just install 3.91s and a 2800 stall TC and in the first two gears she will be a terror in the city. And keep the Dual exhaust and 600, but get you a small-port intake. Even a single-plain small-port.
But if a 4-speed, then make it 4.10s