Build my own 454 or 468, or buy crate engine?

I'm thinking of stepping up to a big block for my '65 C-10. While I can fix small things under the hood, I'm not up to building it myself. I want somewhere in the range of 540-575 horsepower/torque. This is going to be mainly for street use, with a few runs down the track every now and then, meaning it has to be reliable, and run pump gas.

My questions:
1. Can this be done?
2. Cheaper to buy everything I need and have someone build it, or buy crate engine?
3. What kind of price am I looking at here?
4. Would it be simple to add power to this combo later on?

If I don't have the budget to do it all at once, I may just buy parts as I can. I live just east of dallas so if anyone knows any good builders near here, please mention them. All input is greatly appreciated.  

Here's a list of crate motors that are close to your desire hp/tq numbers.

http://www.jegs.com/i/Chevrolet+Performance/809/12568778/10002/-1

http://www.jegs.com/i/Chevrolet+Performance/809/12499121/10002/-1

http://www.jegs.com/i/Chevrolet+Performance/809/19201332/10002/-1

This one's not as powerful but in your CID range.

http://www.jegs.com/i/Chevrolet+Performance/809/12568774/10002/-1

You could build one yourself but it does not come with a warranty.  

The 454-468 BB has been a racing staple for a long time. I ran one back a ways and even with the stock crank, rods and pistons it is still a pretty good runner.
Add a decent cam, heads, carb, intake, and headers and your goal should be in reach.
Building your own is generally cheaper but you have to have that ability.
It would depend on your skills and wallet too.  
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