I'm using a termoquad on a Performer manifold and headers on my 440. I've searched and done alot of reading on the subject, but its not clear whether the exhaust passage under the choke well will warm up without the stock exhaust manifold valve to force exhaust through the passage. Will it warm up enough to use the stock spring-style choke?

Thanks

It will take longer to heat up, so I would try to get the choke that is electrically supplemented too, like many of the later ones were.

I would block off the heat cross over. Usually if your idle circuit is adjusted properly the engine will run fine with out a choke. The engine will run better at higher temperatures with the heat cross over blocked off. If you do a lot of cold weather driving use a manual choke and hide the knob under the dash.

What is a termoquad ?

YOU are cool ...with an alum intake. It warms up muchO bester and way quicker than an iron one.

Will the intake warm up sufficiently to pull off the choke if the crossover is blocked? Or should I leave the crossover open?

Have look at this thread , may answer some of your questions.