Dash mounted radio

[yellowpinky]

I'm thinking about 're locating my car radio from the passenger glove box on the late minor, to under the dashboard... so... potentially a bit of a job, as there's a metal seam under there that's right in the way to mount the radio flat...
So I'm thinking of removing the seam by stitch drilling, then cutting & filing just where the radio goes...
but is this gonna weaken that area too much? is this a bad idea?
if I decide to do it I'll also be looking for a cradle housing for a vintage radio, does anyone know where to get them & are they a universal size to fit all?