47-59 Vintage radio and antenna question

[fauXGT]

I just plan on utilizing the rear 45W X 2 rears from the radio going into 2 6X9's into a 'as large as I can squeeze into behind the seat and still hide' box. Not going for the cheap 2 single boxes, but something with a bigger enclosure for lower frequencies.
Not putting in a separate sub and amp, which I do have, but don't want body panel rattling on a classic truck like these. I'll have the engine rumble from a V8 to play with. 180 watts from the radio will be plenty for this old guy. + a decent 6X9 can give you down to 35hz if in a good enclosure.