doing engine swap

I am trying to find a blockoff plate to go where the heater core and a/c assembly all was. I have tried to look around but no luck at all. FYI - doing 454 in my buick :rofl: :rofl: :rofl:

The year of my buick is an 1983.

i temporary put in a 350 i had laying around until i can hone out the cylinders in the 454