Ditch all of that.
I went w the Breman Blaupunkt head unit in my 87 coupe
New door and shelf coax speakers and this subwoofer under the passengers seat with a built in amp.
My system sounds amazing, and i've put a similar setup in my 89 560SL and 77 Scout Traveler.
Pyle amp'd sub:
https://www.amazon.com/gp/product/B09F7MB8LC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
-Ian