I did a quick scan of the thread, didn't see these things, forgive me if this was covered already.

-looks like you changed the vac spring before the engine was ran w/ this carb. Very easy to get the diaphram off center. Could have a huge vac leak at the pod.

-are you running a choke? I was having fits w/ my 3310 and another member pointed out that there is a hole that needs to be plugged if it is removed. Looks like a screw hole, I didn;t even think it was anythign until that was pointed out. I put a self tapping screw in and my carb now runs fine.

-I bet you have a vac leak someplace. If not at the above spots, someplace. Have you went over all of the intake areas with carb cleaner to check?

-how sure are you that the TDC mark is reliable? Maybe you have a bunch more timing than you think.

-have you tried different gas stations?

I really find it hard to believe that a 9.2 to 1 engine w/ aluminum heads pings on 93 octane w/o any vac advance at all. The jets you have in there just sound way too big. The plugs should be pretty dark, unless extra air is coming in somewhere. There has to be something missing in this picture.

You need to find the problem.
Lower rear gears and spark plugs won't fix a carb problem.

There are two things that will make it sneeze back when you punch it, slow timing and/or a lean condition.

10 sizes larger on the jets is crazy. It may eliminate the symptoms but the problem still exists. Seldom does any motor with a Holley perf carb need more than 4 jets sizes up.
My first guess is you have a problem with the power valve circuit. A bad power valve, a power valve with too low of a rating, or a stopped up passage.
My second guess is it's lean on the accelerator pump circuit. Nozzles should be big enough if it doesn't sneeze when you hit it from an idle. Make sure have a pump cam that still has travel from half to full throttle.
If you want to eliminate the chance it's the secondaries opening too soon, disconnect them and try it on primaries only. BTW, the spring has only a small effect of when the secondaries open. The main control is something called a kill bleed. Although one will effect the other, basically, the kill bleed controls when the secondaries start to open, the spring controls how long it takes to get them fully open.

Remember that there are 5 fuel delivery circuits in a Holley.
-idle ports, from the idle mix screws
-transfer slot, near the idle ports
-acclerator pump system, delivers fuel to squirt nozzles
-power valve system, delivers fuel to boosters
-main jets, delivers fuel to boosters

The goal is to find and fix the problem, not just eliminate the symptoms.
You have understand how something works before you can fix it, GRASSHOPPER.

If your spring is compressing, I'd aim your efforts there.

Let's assume the spring is weak or there is too much resistance in the squirter circuit. Switching to a hollow shooter screw AND/OR shimming the spring will help.

Unlike bigger jets and bigger shooters. This modification will not consume more fuel.

I'm really unfamiliar with the power valve system. When does it start to work and what would be symptoms of a bad power valve? [Edit - never mind, just read through some info on Holley's site and it sounds like mine is still working and wouldn't be the cause of my problem regardless.]

I can't really try anything until it quits raining here and that's going to be a few days.

Going to go pick up a 3.23 gear set in a 489 case today. Isn't likely to solve all the issues but will be a better overall gear set for my combo.

Pick up a can or two of carb cleaner while you are out.

Maybe I never said I did that but I sprayed the entire thing down with a can of carb cleaner while I had it off the engine to convert it to 4150 and rebuild my fuel line last weekend. It made no difference in how it works. But it is all shiny and clean on the inside now.

You need to check for leaks. Not about cleaning anything. You are about 99% sure to find that you have a vaccum leak.

Gotcha.

Nothing in the intake runners to indicate that it was sucking oil. I'd used a full set of intake minfold gaskets on both the top and bottom of the bath tub pan. I guess I need to figure out how that is going to work because what I had on clearly didn't. And I used Gasgacinch to seal it up even.

Spray copper adhesive holds them tight also...

Time to run it over to the machine shop I guess. I resealed the entire thing with new gaskets and it still pings when driven and still bogs slightly when I spay carb cleaner under the intake.

Okay, I sealed up the intake one more time. Now, I cannot find a vacuum leak at all.

Still pings.

I installed a 3.23 gear set.

Still pings, but at a different speed (though I cannot tell you exactly because I forgot to pick up the speed-o gear for this setup -- tires are 26" tall).

i read about it since the beginning and because you tried different timing positions, i dont think its timing-related. a couple of years ago, ihad a similar bog at part throttle and a bigger shooter didnt correct it. a high flow power valve did, and i suggest you try holley number 125-165. first confirm it is the primaries that are lean by disconnecting the vaccuum pot from the secondaries by removing the small clip at the end of the shaft.make sure the secondaries cannot open and go for a ride. if it still bogs or pings you know the problem lies in the primary circuit and you should try the hi-flow power valve. you could also try to momentarily plug the pcv hose with a pair of vise-grips, it should help too.

I disconnected the secondary vac can and locked the blades shut. I went for a drive and it pings just like it always does.

I've never heard of one of these high flow power valves.

By the time I'm done with this there will be nothing original left of my 750 Holley that "works" right out of the box.