a/c help 73 gmc p/u

[frankyjoet]

i have a question about the fan cage hole on the firewall. i have a wider fan cage bought from autozone attached on my new a/c/ heater motor. Do i have to make the whole larger on the firewall. i know the motor gets attached to the evap housing. Is the old hole opening now good for air flow? thanks for any help. I am ready to install the evaporator , fan motor and housing to wall. frank 73 gmc 350 rv old granny 4 spd 3/4 ton