Restoration of Original Radio

Does anyone have experience in re-installing an AM radio back into a dash that's been cut out to accommodate an aftermarket unit? I would imagine that some type of bracket or other support needs to be added to hold it in the correct position, but I'm trying not to reinvent the wheel.

On the same subject, how do you access the top-of-dash speaker to replace/repair it?

This is in a '66 Barracuda, BTW.

Thanks.

Steve