High(er) Current AC Flasher Circuit
The circuit you linked to is for low power use. The 10uF capacitor provides little energy. All the current for the load (the led) goes through the diac, which has limited capability. 

For higher power you may want to look at strobe lights. They work on the same principle as far as the timing goes, but the timing circuit triggers a SCR that them conducts and discharges a much larger capacitor through a xenon flash tube.



http://www.free-electronic-circuits.com/circuits/strobe-light.html

This is a basic circuit. It will give a lot more output than the led circuit but still may be underpowered for your application. This is a simple circuit and a professional design would be a bit more involved because of the power required and the reliability needed for the application. 

It is recommended that pulse grade capacitors be used. Photoflash capacitors are designed to discharge into flash tubes but they are not designed for the repetitive cycles that a strobe uses. 

With higher powers it is desirable to have an inductor in series with the flash tube to control the peak current at the start of a discharge cycle. 

There is a lot of engineering that goes into this type of device. (or there should be) There is a lot of information available on the internet, some of it is very good.