Speaker replacement - 6"x9" or two 4"?

[Praxiss454]

I found a working GMC AM radio for my 65, but I don't have a speaker. I'd like to so something fairly low cost to be able to listen to the radio. It looks like a 6"x9" would fit, so I was considering a cheap one on Amazon. If it fits this should be fine for a mono AM radio.

So my main question is will a 6x9 fit up there in the original spot?

Another inexpensive route I was thinking of going is two 4" speakers. The benefit here is if I add an Aux input or small Bluetooth receiver/amp I should be able to figure out a way for it to be mono for the AM but stereo for the Bluetooth receiver.

I so far don't plan on modifying the radio as a working GMC AM radio is hard to come by.