Updating to help anyone in the future looking for this info. With a 2.5” pulley and dual idler pulley’s, a 59.2” belt will work, and is what I currently have installed but I’ve had to max out the tension adjustability on the blower to get it tight enough. I have not driven the car yet, as I have yet to install the oil pan. I have ordered a 58” belt that I’m going to put on after I get the car running and any bugs worked out. With the 59.2” belt there is easily two to three inches of slack making it super easy to install, but like I said it requires you to max out the tension on the charg