300hp would be quite a bit of work as the stock LA 318 only makes around 180hp stock. I would be going for torque, personally. If you're going to pull the engine, freshen it up and perform the work you speak of.
Hell, if you're looking to spend that much money you might look at swapping in a Magnum 318 and carb it instead. At the very minimum I'd be looking at aftermarket heads to replace the factory SMOG heads on the current 318.