375-400hp 360?

To reach the HP goal, then more needs to go into breathing parts (valves and port work or better heads, intake, headers). But, the Speed Pro H405CP's are the least costly pistons that will bump the CR up at all (that I know of) and that won't require a rebalance and that associated cost (which will be several hundred $$ if you just let a shop do the whole thing). If you use .028" thick head gaskets, and those pistons your CR ends up around 8.5 for stock chambered heads. That is not a bunch more than the stock CR so with a larger cam to get high RPM breathing up, the bottom end torque will be compromised to some degree, and that is not good for street cruising.

So you are kind of at a crossroads on this type of budget: put more into the bottom end parts to get CR up more and help the low RPM torque , or let that go and live with the less torquey performance on the street. Too much sacrifice of low RPM torque with the stock torque converter is going to end up with a low RPM range where the performance combinatoin is sluggish. If the compression stays low, then the cam can be made smaller to bring low RPM torque back up, but then with the stock heads, the high RPM HP will drop and you won't meet your 375-440 HP goal.

SO IMHO, it would be good to think about what you want the most: street torque or that HP number. Is the car mainly for drag racing or street cruising or commuting to work, or???