I just used the heat exchanger. I will do the option b and dual pass eventually.

 

Thanks guys for all advices! I'll put a 2.99 pulley and a second heat exchanger and an aeroforce scan gauge.

Still have a couple questions though:
Do I need the "option B" with a second heat exchanger?
There is another place than GM to buy a 76mm pulley ?

Thanks, Fred

 

you can get the pulley from smoothflowpulleys.com or crateenginedepot.com