Stock Mopar 6×9 speakers in the old oval speaker holes in the trunk?

Greetigs Learned Moparians!

I'm looking for good fitting speakers to drop into the oval holes in the sheetmetal behind the back seat under the rear window. I think they measure 6" x 9" W x L but the ellipse made then might not exactly conform to modern 6 x 9 speakers. How many of you have tried installing modern speakers in that spot on your Slab sided or even fuselage bodied cars? I guess even Formals probably would more closely match things made a mere decade before them than modern...

Stock Mopar 6x9 speakers in the old oval speaker holes in the trunk?