That's a rare failure. I researched timing chain failures in the 1GR-FE engine extensively after I bought my 4Runner project last year, and did not find a single breakage. Plenty of elongation due to wear, especially in the '07 manufacture year.
I posted notes and pics somewhere here that may help w/ your project. And like I said earlier, the Cloyes kit seems to be a good balance of cost & quality. They're a very reputable company.
As far as yours goes, you can check for bent valves after you get the valve covers off. Rotate the crank to put the balancer zero stripe right on the timing tab zero mark, and then *gently* rotate the intake cams (and exhaust as they're chain driven off the intakes) to put them at their respective zero marks. If the cam stops turning and you hear/feel metal on metal, reverse direction and try again. Then follow the shop manual guide to check clearance between the cam lobes and valves w/ a feeler gauge. You'll get most, but not all, valves this way. You can check the rest by rotating the intake cam while watching the cam lobes that were on lift, and check them when the lobe is past the valve. Bent valves will show up as excessive clearance.
