At that amount of boost your just rolling the dice on a cast crank. Basically you've pulled the pin out of the grande and the only thing holding the handle down is a piece of Scotch tape. It's going let loose at some point, but you just won't know when. It really is matter of how long you want it to last and the budget you have to make it last.
Depends on the end game. If you're buying all aftermarket rotating assembly they all cost the same.
What compression ratio are you intending to build? Because this is a major issue when it comes to getting an off the shelf piston that will work in ratio lower than 9 to 1.
Anything lower and your looking at a custom made blower piston set which start in the $1800 range and up depending on what you want, or need.
There are several other areas that require attention if you really intend to bang on it as well.
You didn't mention if this is a 340 or a 360 this also has significance in what is available crankshaft wise and what connecting rods you can run.