How much hp is a stock block good for?

I have a DSS 306 with a main girdle and a s-trim. How much power can this block take. I have 525 rwhp now I wanted to know how much I could go up to.

Thanks
Scott

U R already past that point..i have 600+rwhp & waiting 4 the big BOOM..

You're already at it's limit even with the main girdle support. Stock blocks are known to split right down the center of the lifter valley at the power level you're at. Keep the revs under 6000 and you should be fine, but forget trying to make more power and expect it to live a long happy life.