Installing Vintage Air- A/C Padding kit on Firewall needed if installing Hush Mat to the Firewall?

[Rikker]

I have a 1969 Dodge Charger 440/570HP. I will be installing Vintage Air. The car is newly painted and just a shell which I hope will make it easier to install the Vintage Air. I plan on installing Hush Mat throughout the entire interior. My question- is the Fire Wall Padding kit necessary if Hush Mat is used and to anyone who has installed the Vintage Air does the A/C padding kit get in the way? Any suggestions will be helpful. Thank you.