Update:
Well it is now Tuesday, and the distributor, for my 53' Merc convertible with a Merc-a-matic, was set to the correct specifications on the Sun distributor machine on Sunday, by a local club member, that just happens to restore them.
The issues were, hesitation at a stop sign to accelerate along the feeling of a "flat spot", when accelerating at speed, and high temperatures (200+) when climbing.
The distributor was set to the specks found in the Vanpelts chart (per Motor Auto Repair Manual) attached, for Late 1950 to 1953 OBA-12127.
http://www.vanpeltsales.com/FH_web/f...53_239-255.htm
Before, when accelerating away from a stop sign, the engine would hesitate, forcing me to "feather" the accelerator to get it going again. And when at speed it seemed to have a "flat spot", when accelerating.
Now when pulling up to a stop sign the engine is much quieter, slower and smoother. When pulling away, the acceleration is smooth and steady. Now at speed and accelerating, the car just seems to "lengthen it's stride".
The temperatures at speed are now 8-10 degrees lower and the temperatures climbing are 10-20 degrees lower. (I have two separate temperature gauges, that replaced the original temperature gauge and sensors).
One final thought, just maybe the issues you have been blaming on the carburetor, and haven't been able to correct, no mater what you do, just might be able to be corrected by setting the distributor to the correct specifications. Find someone with a Sun distributor machine. You will be glad you did.