Yes those casette adapters will work. Most people, however, just change out the casette player for a CD unit for not too much money. One can be had for under $100. Check out crutchfield.com for some ideas.
That can technically be your first mod
. I recommend that if you do change it out, try to change it for one with at least an AUX jack or USB port in the front so you can plug a thumbdrive or mp3 player to it in addition to a CD player. Good luck and be creative!!