The Booze Runner
 

We have a 383 stroker motor with a 671 gm blower on it. It has two
750 Holley blower carbs on it. It has a 32 tooth bottom pulley and we want
to have 10 to 15 pds of boost. What top pulley do we need. Anyone
know.

Here's some reading material for you. You plan to run 10 to 15 pounds boost, on the street or track only? Fifteen pounds with a roots blower is a whole lot of boost for a street motor, especially with todays pump gas. Figure out your static c.r. then take a look at what your effective c.r. will be with that much boost.

It sounds like you have an older 1/2" pitch setup, not the 8 mm. There are pulley combos you can use to get wherever you want to be, swapping up and down, etc. There are charts in the attachments.

The Booze Runner
 

Thank You for your reply.