Jay I wouldn't worry about the head, I'm running 16psi on a stock head and its fine.
Although in the future as raf said, if your looking to raise your rpm limit, might as well do it once.

My recommendation, would be go with the 10:5:1 pistions.
You'll notice the difference and once you get bored of it, you have a nice setup to turbo in the future. I think I paid an extra $250 for the high comp pistons over the stockers.

I would add some eagle rods though, wont make a difference when your N/A but again if even in the future you do decide to go turbo, you dont want to do things twice.

I think looking at it like " if i'm going to go turbo, I need a tsi or gst ect.." is wrong.

For the money you've probably spent on your car and work you put in, would it not be a big waste to sell it off?

Our cars are good up to 600hp.. if you wish to make more then that in the future, sell your car for a tsi or whatever.

If your cool with 600 or less, keep it and have fun