Serpentine Belt Length Question

[91StangGT5.0]

I currently have an underdrive crank pulley and a cobra water pump pulley. I'm planning on putting a new stock crank pulley on since my charging system is suffering a bit. I do not have the air pump on and I do have A/C, Power Steering, Alternator, etc. Does anyone know the correct serpentine belt size I need?

 

[Celeb]

 

[91StangGT5.0]

I have a Cobra Water Pump Pulley....it's a smaller pulley than the stock one. Will the diagram be sufficient with having the cobra pulley?

 

[Mafia Mustang]

Does this chage With Smaller Underdrive Pulleys.. and Can It be Done To Eliminate Smog and Ac Without Moving the Powersteering pump?