They may not even have it in stock. I’ve owned six packs since 76. I’ve gotten quite good at tuning them. It’s no different than any carb,though. It has to be adjusted to your engine. I’ve had AVS give me fits because of the bigger than stock cam and low vacuum. If your doing a restoration look then they do look cool. If custom, just go with a good AVS 2 or a big Holley type from a known builder.