4100: bog / hesitiation when stomped

OK, I've got a 4100 from Pony Carbs 1.08 bore on a 1985 302 block. .030 over, balanced and decked for ~ 9.3 :1 compr. ratio. The cam is flat tap hydraulic 216 Adv. Duration @ .050... (pretty mild / decent idle) and World Products Windsor Jr. heads, and Edel. Performer RPM intake.... when I give it full throttle, it nearly sends me first through the windshield, then it snaps me back a half second later when the motor gets its act together and it pulls awesome! I'm wondering if this is the carb's power valve / accelerator pump issue or is this a timing / spark curve issue? If I feed the fuel to it rather than stomp it, it works great through a solid power band. Per Jon @ Pony, I've got the timing running max vacuum, so what's my next move? I want to install an MSD distributor (presently running Pertronix in an orig. 289 distributor), but I want to close one chapter before introducing another variable. Thoughts?
GT1966

Well DHearne, you never steered me wrong before! I don't know the degree advance number; I basically tuned for maximum vacuum at idle per Pony's instructions. I read where having had a back-fire through the carb could damage the power valve.... had that happen a year or two ago when I had a firing order "misunderstanding" with my new (early firing order) camshaft! My gut tells me it is not the distributor curve, since the bog is immediate when you punch the accelerator. ....and if the condition was too lean, it would pop back through the carb upon stomping it? I guess if it was spark timing, the reason why it runs fine as I feed the throttle is that it gradually advances the timing, rather than not having enough advance at low rev, wide-open stomp? I guess I'll crank-in some more advance and see if it helps.... however, seems more advance makes the engine difficult to crank for cold starts.
Cliff