It was running ok, now it’s terrible, I need help!!!

I purchased a 1962 Dodge Lancer last December. After I rebuilt the brakes and did some steering repairs I drove the car briefly to check things out. The engine seemed to run ok, no smoke, started and ran fairly well. Each time the engine started there would be a loud pop in the exhaust. I then removed the interior, and spent the past eleven months repainting the car and redoing the interior. I put the car back on the road last week and besides the pooping when the engine started it seemed to run ok. This week I decided to replace the points and condenser and check the timing. Now the popping has gotten much worse, any revving the engine results in popping, on the road trying to accelerate from stopped, results is a series of loud popping in the exhaust, the car wants to bog down momentarily until the popping stops. When decelerating, there is also popping in the exhaust. I don’t know wether the work that I did caused the problem to get worse of if the problem was developing on its own.
The engine is a 1962 225 slant 6, with a 1bbl Holley 1920 carb.
Dwell is 45 degrees, timing is a little early at about 10 degrees. The engine idles well at curb idle and fast idle. I needed to establish TDC as the mark was way off on the harmonic balancer, I did this with a piston stop.
I don’t want to do any unnecessary surgery on the engine so I’m hoping someone might have some insight into what is causing the popping, or miss fire. I have not taken compression readings yet as the engine seemed to be running well before all of this started.
Sorry for this long winded thread, I’m hoping someone has some ideas
Thanks
Bill