I am also going to explain how i repaired my cowl and flushed the wiper holes. I wouldnt normally post tutorials but this mod is very tricky. i messed up my first one due to warping. Anyways you will need to go very slow with the welding and spread it out. i did about 1-2 tacks every 1 minute. I wouldnt go any faster than this. also make sure that the patches fit flush with no gaps. I used a vise grip to keep the patches flush with the parent panel when tacking them in place.
After all the welding was done i hammered the panel as flat as i could make it. the next step is to grind the weld down. go slow you dont want to warp it with to much heat. also i left the rolled lip on the underside of the wiper arms to minimize distortion, but you need to grind this down when your done so that you can shape the metal easier. Another trick is to angle the flap wheel at ~80 degrees to feather the weld bead down without taking alot of metal off. Hopefully the panel is still pretty flat and not warped. mine was still a little warped and i had to use a blow torch to heat the metal and a wet rag to rapidly cool it. this shrinks the metal and gets rid of the "oil" can effect.
Hopefully all these tips will help you repair your cowl and/or flush your wiper arm holes
