If you currently have a carb with manual choke, keep it. I've got a 1406 on mine and I haven't been able to get it to work yet, despite lots of help from ck5. I hate that thing. he'll maybe it's just mine though. If you are dead set on it you need to run a hot wire to one of those fuse box spades, check them with a multimeter with the ignition in the run position and see which one gets power with the ignition on only, then connect your hot to there, then simply ground the other choke wire. Then it should be fine. If it needs adjusted, ask me and I can tell you how to do that.
if you want 12 volt for the choke just take it from the wiper motor
one of the wires is hot when the Ignition is turned on thats how i just did my 87 and a friends 76 k5 the wiper still works the same and you have a choke
No,you dont want anything other than the ignition coil powered by the thick red wire it has...it'll drop the voltage going to it if you splice into it and use it to power something else (especially an electric choke heater element,which is basically a direct short),and reduce the spark intensity...HEI needs a full 12V to work right..
The wiper motor wire might work ok,it could slow down the motor a bit perhaps..
There is at least one spot on the fuse box that only gets power with the key "on" and not in any other position...seek it out using a test lamp and wire it up right..(and be sure the wire doesn't get power with the key on "accessory").