Hey Hinges. Welcome to the wonderful world of street ridding! Remember now. You are doing this for fun. I started building cars in the 70's, Had very little money but lots of determination. My friends still kid me about the junk I have built. That includes a 55 Chevy I paid $650 dollars for and brought a $25,000 bid in Atlanta.
There is nothing there you can't fix if you are determined and want to do it. I believe the key is, you have to enjoy the garage time and the feeling of accomplishment you get when you bring something back from the dead. When I build a car, I focus on one task. That way I get to feel warm and fuzzy when it is complete and I am ready to move on to the next.
If the cowl is going to be the big challenge, find out how far you need to trim back to get to solid metal. Take lots of pictures and measurements. Open the panel up tp where you can access the inner most piece that needs to be replaced. Work your way out and you will eventually have a rock solid cowl. Post pictures as you go. It will help to know the rest of us are impressed and are rooting you on. The satisfaction you get if you do well can not be measured. Good luck.