I've got a 1983 carbureted base 305 that I want to warm over a little bit. I already know that 305's aren't the greatest engines for performance and that it is much better and easier to make power when running a 350.
But I'm not looking to make this a fire breathing racecar. I just want to get a little more power out of what I already have, the 305 is running well (for a stock 305 smog motor) and only has 67,000 miles on it. And I do not want to go to all of the effort take the engine out of the car and replace it.

But I don't mind changing out the heads. I have a set of Vortec heads laying around the garage that I could put on this engine. I would think that I would need to surface mill the Vortecs to get them down to the 305's 58cc combustion chamber size and mill an intake manifold to match.

But I am wondering how the Vortecs will work with the smaller bore size of the 305? Will the head's chamber edges be larger in diameter than the bore in the block? And would that cause a problem?
Are there any other potential problems to watch out for when attempting this kind of swap?

 

You'd be better off getting Vortecs for a 305. They're very similar and already have the right size chambers. I cant remember the casting number off the top of my head, maybe 059? But they're a lot cheaper. Also, remember, you'll have to get a new intake manifold also.