While I may be wrong in this case (because I haven’t really looked, I haven’t seen the vendors with an insulation “kit”....
...but if your engine is out, it’s pretty easy to apply your own insulation on the inside of the firewall. I covered mine with stainless steel panels.
You can also sandwich some thin insulation under the fiberglass bulkhead cover, as well.
Pretty easy, and useful job.
Rocky