360 heads on 318

PHF,
The thing is that you'll not find a better head than the 302's for the street and low rpm HP and torque, but you have to stay with the small valves or the low end performance will be gone. This is what makes these heads come alive and work. In full ported form we have had them up at 6500-6800 rpm's and still pulling, the nice thing is that the small heads allow you to run more cam and make more use of it without any drawbacks. Just make sure that you have all the parts to match the cam and that the engine is able to utilize it.
From having large port heads and small port heads on the same engine the small port heads will have more lope to them than the large ports will, and use less fuel because they are more efficent. And the more efficent a engine is the more power it will make, reguardless of the CI. This is where having the right head on the right size engine and the right cam is where it's at. Making everything match for the engine and rpm use will give you a much more enjoyable time than one that sounds like it will run but wont.