I think Joe is talking about the fulcrum point of the lever. Changing lever length would change hand position to utilize the new length. Turns into a mental issue; changing your whole riding position until you're use to the new hand position via figity uncomfortableness.
I'd rather use a good used 30-year-old factory cable from a parts bike than a new BB cable.
For a used cable; flush it out first! Get ALL of the past dirt and lube out of it. I start with gasoline and finish with alcohol-based solvents such as Naptha. Once flushed, NO MORE PETROLEUM-based lubricants. Petro-lubes will gum up under all circumstances and hold dirt like a magnet making a cake-like "pre-casing" inside the cable. I use "Lock-Ease" lock lubricant. It is a dry graphite powder in a alcohol-based carrier. Flush the cable with it as though you were trying to clean it earlier. Flush it good and let it drip-dry. Work the cable through the casing every so often to help the alcohol evaporate out. When finished with a new-used cable, installed and properly routed, my '78 has a single finger pull lever with a factory spring set.
A benefit is that the graphite "lube" is unaffected by the temperature and humidity. Petroleum is just the opposite.
For a method, I use a combination of tactics to flush-N-fill a cable. Gravity and compressed air combined with plenty of fluids.