If you want a up to date radio with out spending a fortune for an original in a 60's car this is what i did. I mounted the alpine radio w/o drilling or cutting any gm tin. When the car is being judge I slipped a GM era correct tissue dispenser over the alpine. I pick up a used tissue cover in good condition at a swap meet, with a little twinking i got it to fit. It has a remote I can see the radio display. W/o fumbling for the knobs under the seat or in the glove box.
..why hide it??? New radios were installed in older cars back then especially AM-FM's or an add-on FM tuner, ..if you're "worried" about being "traditional." Just do it, ...WTF cares!!! Who cares about the trad police? Back then, it was anything goes. Q: Would you consider a 265 Chevy V8 traditional in 1955? Yes? No? A: Nobody cared, in fact, it was considered forward thinking. Speed, safety and comfort were in!!! ...we now return you to regular programming.
I put a polished aluminum plate behind the glovebox door in my 48 chevy 1/2 ton , and put my stereo and heating & A/C controls in it. Close the door and it looks like a stock dash.
On the sled, I tigged some hinges to the bottom of the original speaker grill hid the "new" radio behind the speaker grill.