Help with hei install

Ok so I'm going with an hei ignition on a point style harness in a 67 barracuda. My question is after I bypass the ignition ballast what is a good constant power source from the ignition that's easy to access. Is it possible to use the dark blue wire that's running from the ballast I bypass or do I need to keep the dark blue and grey traser dead ends ? I'm still learning with the whole wiring thing if you've done this before feel free to let me know how you went about it lol can't find the answer searching on line and definitely need to know thanks in advance