O.K., I need all the opinions you can give me on this one.
I'm looking to purchase a '69 Bird with a 350 2 barrel. Horsepower around 265 as you know.

If I changed out the intake manifold on this 350 engine for a intake that would take a 4 barrel carb., would I gain any horsepower and if so how much?

Could I bring the HP up to around 300 or wouldn't it be possible? What if I also added headers? Would that boost the HP?

Or, would it be better to find a 400 engine with a 4 barrel
and replace it with the 350?

If the new intake manifold idea would work, then what manufacturer would you suggest and also what manufacturer of the new 4 barrel would you suggest?

It seems like 350's are fairly common to find, but 400's are a little more difficult to come by. That's why I'm considering a 350, but I want to boost the horses. I'm not a hot-rodder by any means, I just like to have some more engine response when I start out and passing on the freeways.

Anyway, would appreciate anyone's feedback on this. Thanks.