I've race Mopars and won with them at NHRA races in stock and in the heads up 10.90 and 9.90 classes with BB, SB and 426 hemi.
All the BB like between 34 and 36 total timing at the tracks we tested on, I weld up the stock advance slots and make them have around 16 degree mechanical advance so I can set the idle timing between 14 to 18 BTDC to get the total timing where I want it. I also use a set of real light advance springs from Mr. Gasket, part #95B I think.
As far as the butt dyno, yours and mine probably are not calibrated the same shruggy Most butt dyno normally won't feel .030 to .009 ET and or from .3 to 1.5 MPH gain in the 1/4 mile shruggy twocents The time slip will show those changes accurately up scope
Tune it to you like or love it and then read the real results with a good timing light twocents scope

Last edited by Cab_Burge; 10/03/21 10:53 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)