If I could sit in your rig for like 30 minutes I could likely design something but as it is we get to play 20 questions...
now... You said a dual cassette.. this shounds like a house "Deck" not a dash radio.. If it is then here is a recommendation.
You need a good house radio with Sirus capability, Best buy has dozens of these on the shelf.. Any good system will do.. These run on 120vac.
You need a DVD or Blue-Ray player with A/V output These will also play CD's.
You need a new HDTV.. If you do not have sat-TV then feed the Blue-Ray's HDMI direct to the TV, feed the Right and Left (Red and White) A/V leads to the home theater/radio's AUX input (or CD input if it has one).
As I said this is all easier hands on. But it is all off the shelf at any Audio/Video department.
I am in Upstate SC if you are nearby PM and we can do a eyes on job.