Old Online Chevy Manuals does not have 1949 truck. Just a 48-51 truck and a 1949 car manual. The car is hand op. In the 1949 car manual is also says when new rear shoes are installed it is necessary to adjust the toggle lever with the parking brake link by means of the eccentric bolt. May or may not be of interest. A picture is included in the 1949 car manual.
The only answer I see regarding your question on how far to "pull cables out of the conduit" is: "As far as possible" (truck) and "until positive stop is felt" (car). That's it, that's the answer from the manuals. Then tighten nuts.
During E-Brake adjustment, one wheel may lock better than the other. Manual says adjust that other wheel at that point. Maybe if all else fails, that you can eliminate the 1 1/2" preload (or some of it) while adjusting and see if that helps. I know it's there so that the return spring(s) can operate using a little slack.
Talking down was the wrong word. Just tried to say I didn't realize you were a GM Factory Trained Technician. Automotive restoration and design, teaching, drag racing person.
