The Thermoquad was a pretty good carb in it's day, but they were not without their problems. And as with any 50 year old carb, they were designed to run on a very different fuel than they would see today. So, any Thermoquad would need a bit of work.

The Street Demon was designed by an former Carter engineer, which is why it is similar to the Thermoquad. But it has a number of design features that set it apart from any other mild street oriented carb out there including the Thermoquad.

Go with the Street Demon. As mentioned, the only issue that might be encountered is the choke housing.