Firewall Holes, need to plug. Please help!!!

[1972BlueC20]

I have 2 holes in my firewall between the little dip in the heater box between the heater core area and the fan motor where 2 hoses used to come through for my aftermarket (original dealer installed) clardy AC knee knocker system.

I no longer have this AC unit, so now I have 2 holes I need to fill.

I have no skill at welding nor do I have the gear.

Seems like I should be able to find some kind of rubber plugs.

I think the diameter is like 1.5 - 2 inches.

Any idea what I can use to plug these holes?

I had black duct tape over them but it was really ghetto haha