There are lots of threads here on the BB for SU tuning problems, many in the 120 section. Currently one is near the top of the list. Comments by Phil Singer, who is also in Portland Oregon I think, posted this
Questions re: SU tuning
You might be able to tempt him to look at your carbs, I'm only saying might to cover myself.
With reasonable summer temps you should be able to push the choke back in a third to a half, virtually as soon as the engine starts. By the time the water temp gauge starts to come off it's stop, the engine should run along steadily with no choke but it may need a tweak out again if your first junction is only a few hundred yards down the road. By the time the needle is in the middle of the green all should be running easy. Any time it's chugging and putting out black smoke it's way over rich. As the SU doesn't have a pump jet for a bit of extra juice it has to balance itself out until the motor is warm. Pumpng the throttle when trying to start doesn't do any good but putting the pedal to the floor will clear out any excess fuel for a while. You give it a bit of help by nudging in the choke in the first few minutes of running, takes a bit longer in the winter. When the engine is up to temp you should be able to reach in and turn the key for it to start and settle to normal idle without touching anything, choke or throttle. That normally proves that all of your settings are just about right.

Currently yours does sound as if it's running very rich. If both the jet settings are about 12 flats down, maybe +1/-2, it sounds as if the one or maybe both of the jets are sticking down to some degree. With the filters off you can check how they work through the range of the choke control, they should both move the same, but when you next go out and it has the problem, just stop the car, leave the engine running and physically see if you can push the jets up. DON'T burn your self on the exhaust manifold!