Thanks for the clarification on the Street Demon, AVS, TQ operation. I was struggling to understand how they could be vacuum operated without a diaphragm can. There's a few good nuggets of information here that have been helpful. I'm definitely going to go with a mechanical secondary. I have another Holley that needs a rebuild. It's a List 6711 which was a direct replacement for 71-73 340-440 engines. It's ugly but I think I'm going to dunk it in the ultra-sonic tank, face the body and blocks in the milling machine if they need it, and throw a gasket kit at it. $45 may get me a decent carb that should have good throttle response. It's setup for a divorced choke so I'm going to have to see how I can adapt it to manual operation. That should be fun because Holley said they don't make a kit for it. If this doesn't work out, I'll have a hard look at that Street Demon and Brawler.