Holley 870 street advenger - junk?
Why? There's a relationship between the IFR and IAB with the T-slot that needs to be balanced not only for AFR but also for where it begins to taper off for the start of primary booster flow. Not having a go just trying to understand what you're trying to achieve with the changes.
Also when you run locked timing you assume the engine wants that timing at all rpms to produce peak cylinder pressure which is not the case.