Tips on selecting Pistons??

You're moving out of the mild enthusiast spot into more of the specialized area. Best thing I can do really is give you what I'd be asking if I were working with you on it...
You said altitude, and "strong street car". Do you need power brakes? What can you do for regular maintenance? What can you live with for noise? What fuel type? Will you ever go out of the mountains with it? What's the actual budget?

In order to decide on internal parts - you have to know what you have to spend and what you want from it. RRR's idea is probably close although I prefer the Keith Black versions. But a forged unit might be better suited to your use depending on what you consider "fast" or what you need.