Do i have the right clutch fan

Does car overheat (puke out coolant)? What temp gauge are you using? When you say "hills and heat", what's the outside temp and how big are the "hills"? Sounds like your 160 thermostate is the problem, I run a 180 in my 408 with a very similar cooling set up to yours and it runs right at 180, even in 105 degree humid summer heat.