Best manifold for ThermoQuad-equipped 340

I back what RustyRatRod says. The Action Plus is basically the same internally as a Stealth.

As for the Thermoquad carbs, I stayed away from them simply because I don't know how to work on them. But I am building a TQ equipped class car and luckily the previous owner knows all about them and is trying to teach me. He recently had some mid 1.3 60' times in his 318 TQ equipped SS Aspen running 10.60's @ 124! There are plenty of small block TQ equipped Stockers well into the 1.40's. Not sure if any hit 1.39.

Good carbs that can be a pain. Bottom line is that you just have to know how to work on them.