i did my engine bay somewhat similar. I dont have a nice clean pic since its a work in progress but a simple piece of sheet metal and I sealed it with some silicone worked just fine. I didnt put in the other part of the cowl. at least not yet, dont know if im going to.
I would think the bondo on the firewall would crack really fast due to the heat and vibration. your better off doing the whole firewall fresh but thats just IMO.
I would think the bondo on the firewall would crack really fast due to the heat and vibration. your better off doing the whole firewall fresh but thats just IMO.