Compression
Ignition
Fuel
Is what makes our engines run.
Sounds to me like your mechanical Valves are all set too tight.
Just want to make sure you did not set them like hydraulic lifters with adjustable rockers, where you go to zero lash then down 1 full turn.
Solid lifters and adjustable rocker you want something like .015 ths gap with the feeler gauge, not zero lash.
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Then next carb selection comes into play next. Believe your older mopar carb you have there is plugged.
A 1406 Edelbrock usually runs good on the small blocks, the 1405 is a richer jetted carb and can be adding to your problems.
A quick compression test on a couple of cylinders will tell you if your valves are too tight.
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I am fortunate to have a proven good running engine on my test run stand that I use for testing carbs.
Friend brought by a 1400 Rebuilt Edelbrock for me to test run. Immediately ran bad, a lot like the way your engine is running. Dead and popping on acceleration. changed metering rods, springs, adjusted idle jets, No Joy.
Pulled off that 1400 carb and put on my known good 1406 Edelbrock, and it immediately fired right up and ran perfect. You could just tell by the tone of it that it was right.
I am not hearing that good tone with your engine running in the video with the 1405 on it.
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