Well . . . first off, that kit is .030 over. That means you will have a 306 instead of a 302. You will have to have your block bored .030 over to use this kit. Whether you will feel more power depends on what else you do with the motor (heads, cam, intake). The pistons included in that kit are forged pistons, but not very good ones. They are also flat tops and will give you a fairly high compression ratio (assuming your future power adder).
If you are building with an eye towards a future turbo application, you need to look into dished pistons that will keep your compression ratio a bit lower. Somewhere right around 9:0 or a little less is perfect. And, if you are doing forged pistons, you should also consider forged rods and a forged crank.
Depending on how much power you want for the future, you also need to consider the limitations of a stock block. The stock blocks are known to split at around 500hp (this is a much debated topic).
If you have never built a motor before, I would not reccomend that you try to build a motor for future turbocharging. You would be much better off getting a built short block from one of the aftermarket companies. If you can aford it, you should consider a Dart or World block.
