Todd when I repowered my 1210 I used what's called "Roll Plastic" racers use it for body stuff. Here's a link.
https://www.portcityracecars.com/Bla...920801-10.html
All you need to do is cut a strip with some shears, roll it in a tube and bolt it to the firewall. Pics are of the 1210 with the 16 HP Vanguard.