Do all A bodies have overheating problems?

The fire is always in the cylinder heads,lol :), But Ima thinking you mean in the exhaust ports and headers/manifolds.

Yes the big part of the bang should be when the piston is just heading down exposing the hottest part of the flame to the cylinder wall and it's water..not at its hottest exiting the head and exhaust because of late timing.An easy check is glowing headers at night.