Setting Big Block Idle & Total Timing

[donut]

If your retarding the timing, you can keep bumping the idle to keep it running. Just opposite of advancing it. (If you start at about 4* and advance it, idle will go up. Just have to drop it back as you go.)

Beyond what your set at now is trial and error. My dually is currently at 14*, I haven't checked to see if I can use more. My smallblock would start back-lashing the starter at 14*

Total timing (IMO), isn't quite as important as how quick and if it's even functional. Normal driving, I don't run into the issue of higher rpm. My Trailblazer, with the roller engine, on the other hand, will quickly see 5k if I go to pass someone.