power source for choke
A so called "standard" single pole single throw "Bosch" relay
The coil is nos 85, and 86
The contacts are no 30, and 87
So ground either 85 or 86
cut your dark blue coming out of the bulkhead before it spits off to the ballast and regulator
Run the dark blue that you cut coming out of the bulkhead to the one you did NOT ground, I.E. ground 85, dark blue to 86
Now run a fused say, 20A good quality fuse holder, or automatic reset breaker, from the start relay "big stud" to no 30
Now run no 87 to the OTHER end of the "dark blue" that you cut, which feeds off to the regulator and ignition. Also from this no 87, run over to your choke.
Mount the relay AND FUSE (or breaker) away from weather and engine heat. Probably the best place is over on the firewall/ fender near the ballast.