The 'Ebay' and '$100' HEI clones have been killing engines right and left, so I suggest you do a couple of tests to find out if you are becoming a victim.
First off, you need to remove the distributor,
Take an 1/8" drill bit, and rotate the distributor gear 90° to the roll pin, and try to drill the apron of the gear.
If you can't drill directly into the gear, it's HARDENED STEEL instead of ductile cast iron, and it WILL eat up the camshaft gear!
GM HEI vs. Motorcraft/DuraSpark Ignitions
There is a HUGE batch of housings and shafts that are TOO LONG!
This loads the oil pump too much, and wipes out the oil pump and the drive gears.
For this one, Install the distributor WITHOUT the gasket in place,
Make sure the distributor flange SEATS ON THE TIMING HOUSING... WITHOUT THE GASKET.
IF so, then the housing isn't too long.
Once the distributor is seated WITHOUT the gasket,
Hold the distributor hosing in place with one hand,
And lift up/down on the distributor shaft with the other.
See if the shaft has some play in it...
(Should be about 0.035" or more, so it's noticeable with just your bare hands)
If the shaft moves Up/Down, then the shaft isn't too long and you are ready for reinstall WITH the gasket.
Your stumble off idle,
There are TWO things you should do to cut down on that 'Bog'...
The first is to drive 55 MPH or so, on flat, level ground, without moving the throttle pedal...
This is called 'Part Throttle Cruise'.
You should take a vacuum reading from the carb base plate or intake manifold at Part Throttle Cruise to determine what POWER VALVE you need.
Most times, with Street/Mild Trail Vehicles,
you will want 2 In.Hg. difference between Part Throttle Cruise vacuum and the power valve opening point.
If your Part Throttle Cruise vacuum is 8.5 In.Hg.,
Then you want about 2 In.Hg. lower power valve, around 6.5 In.Hg. so the Power Valve stays closed during cruise and saves gas.
If you run trails heavily, you might want to increase that gap to 2.5 or 3.0 In.Hg. so the power valve stays closed when you are trying to 'Finesse' obstacles...
If you rock crawl or blast wide open in mud pits,
You might want to block off the power valve all together, and use larger main jets to compensate.
If you use your vehicle as a 'Daily Driver', you might want to 'Lessen' the difference, 1.5 In.Hg. difference so you get fuel faster when you are jockeying in traffic.
Your bog should be worst from standing start if it's an accelerator pump.
It shouldn't be so pronounced when coming off idle from rolling start,
If so, it's from fuel starvation when you open the throttle blades.
There is a transition period, when the blades first open, where the idle fuel isn't sufficient for the air flow,
And before the main jets supply enough fuel for the larger air flow...
This is where the ACCELERATOR PUMP comes in...
It delivers raw fuel to the intake to soften the transition period.
You probably aren't getting enough accelerator pump shot for your engine.
You will find a rod that connects the External Accelerator pump arm to the throttle blade linkage.
There will be adjustments at both ends of that rod.
One set of adjustments determines how MUCH fuel is injected into the intake,
The other adjustment set determines how LONG the accelerator pump shot lasts.
I suggest you try a different adjustment, play with it to determine if you need more fuel, or fuel longer to elminate the 'Bog' or 'Stall'...
Once you have taken care of that 'Bog', and you can highway drive your vehicle...
And see if you have a 'bog' in driveability that HEI distributors often cause in AMC engines...
When you are at 'Part Throttle Cruise', try accelerating a little, but just a little...
Like the vehicle in front of you speeds up, and you are trying to keep up with it in traffic,
Or you were to go up a hill...
You will PROBABLY (most likely) have a 'Bog' when you try and accelerate lightly at 'Part Throttle Cruise'.
Some people have 'Spark Knock', 'Ping', 'Valve Clatter' or what ever you want to call DETONATION, and no matter what you call it, or if you can hear it, or just feel it as a power loss, it's slowing destroying your engine!
This is because the HEI was never designed to work with an AMC engine, and it's laying in WAY too much advance at once!
If you take a look at the link I posted above,
Take a good look at the broken valve and ruined piston
The fix for this is an 'Advance Limiter' for the vacuum advance. You will need to take some of the total vacuum advance out of the system,
And it's EASY, but you will need to fabricate a limiter,
OR buy a specialized vacuum advance canister for about $30 or so...
Let me know directly if you have this part throttle 'Lag' or 'Bog' or 'Knock' and I'll show you how to fabricate and install a limiter for a dime...