HELP! Need 318 Head Suggestion (info provided)

Your set up seems pretty well thought out for what you want out of it. The chambers on your '72 318 heads probably aren't that big. They could be, but I would say that 74cc's is probably the absolute top end, its more likely that they're smaller than that. I'd have them cc'd to get their exact size to calculate your compression. Also, if you haven't torn the engine down yet, measure how deep the pistons are in the hole. The KB hyper's have a taller compression distance, you should be able to compare them to your stocker's to figure out how deep the pistons will be, which will also give you a better idea about the final compression ratio.

The stock heads will be absolutely fine for 275 hp. I would have them redone with 1.88/1.60 valves, but that's all you'll need to do. With those valves the stock heads should be fine for up to 300hp, maybe a little more. 275hp would be no problem.

I definitely wouldn't spend the money for the Eddy heads for the set up and results that you want. If you REALLY want to upgrade the heads, buy a stock set of Magnum heads and a new intake. You'll be money WAY ahead over the Edelbrocks, and with your performance goals you won't notice the difference. Keep in mind that with the Eddy's the price of the head isn't the only thing you need to look at, you'll also need to get their head bolts and a better head gasket since most recommend MLS with the Eddy's. And running an MLS head gasket means you should have your block surface refinished and...and...etc. I looked into getting Eddy's for my 340 build, which I set up for ~450hp. There's a lot of "extra's" that become necessary with the Eddy's, and the price adds up. Plus, I wouldn't run 8.5:1 with aluminum heads. Most folks usually spec an extra point of compression for aluminum heads, I'd want at least 10:1 with the Eddy's because they dissipate heat much faster than the stock cast iron heads.