That is how I do mine. There is a wire on the alt. that is only hot when the engine is running. This way the choke only starts to open when the engine is running and not just because the key is on.
Using original Wiring thats incorrect.
The big stud is allways hot since is linked to batt
Using field green wire on pre 69 cars will be sourced from voltage regulator, so is incorrect to source from there, since is exclusivelly for the alt signal
Using field green wire on post 70 cars is ground, so won't work
On post 70 cars you can use blue wire running to alt field, which is ign key run circuit
On pre 69 cars, the blue wire runing to coil comes from ballast, so is also incorrect. On post 70 cars this wire becomed brown
The ONLY source you must and can use is the RUN circuit ( blue wire ) feeding the ballast or volt reg... On post 70 can be used the blue alt field too.
You can install an oil sender providing a switch signal used on way laters cars, what, with a slight modification on your wiring, can become on a switch on signal to the choke which it was the purpouse of them. This Oil senders are idiot light kind, but 3 prongs, one prong to oil bulb on cluster and the other two are in and out signal from run circuit what is switched on JUST when engine is running, sensed by the oil sender. Will require a custom wire job, pretty much easy to do