Fighting A ping issue, SBC 383 TPI.

Running EBL Flash MPFI in a 1989 K1500.
385cid, FIRST TPI, 36pph gen4 Bosch, mild hyd roller Erson, AFR Vortec Eliminator heads, shorty headers, NGK BKR6EIX, 700r4
Just changed to this injector from gen3 34pph and wanted to go a grade lower fuel to 87 octane- previous dyno tune was just OK on 89 octane. Issue is getting audible ping on moderate to heavy throttle around 3600-4000 rpm, 80-95 kpa area, the tuner and myself have pulled timing back and I've run multiple VE learns- things are marginally better but still ping is an issue. I haven't smoothed or added fuel manually to area.
I haven't put a compression tester on as yet maybe today, the pistons are dished, build was spec for 9.5ish- perhaps octone tolerance is an issue?
What has the experience been out there?
One other question about intake track using 3in pipe from diesal filter going around battery, options are limited but I wanted to know when available charge air is lacking?

I can email log, won't let me post.

sometimes the long runner manifolds need a substantial dip right at max torque where the runners are working the most efficient and just dumping in airflow then you can ramp it straight back in as the flow tapers off
Attachment 13253

You know- I've seen that in a previous tune.
How about the choice of plugs?

Well, spent yesterday and a chunk of change tuning.
- felt good on the highway and up hills where I spent the rpms- probably really slow taking 1 deg out at a time. Felt OK until I goosed in town and she didn't like that at all- lot of work to do. Starting to think maybe 87 isn't supported. Worst case is to travel on 87 and haul on premium. I haven't looked at anything yet. Tried SA from 3004 and it scared me, so went to the 3005 350 bin. a little better. Very short log.