You have the choice...
There are companies offering modern technic behind a classic, universal frontend, like "Becker" does for European standard sizes.
Also you find companies, converting your old orginal into a modern radio with cd changer, BT freespeak and USB....

Just depending on how much you like to spend....

On a Ramcharger it´s easy, i left the original where it belongs fully functional and placed the new radio unit into the center console...

Do you still have the original ?
Think of placing a new unit somewhere invisible (e.g. under the seat).
Lot´s of new radios have remote controls. So handling is not a problem and you get used to find the cd slot very fast...lol
There are also special "flat" subwoofer units available, they are about 4" hight and fit under the bench.
That´s how i solved it in a 73 Dart with bench.

Regards Muskote