Ready to shoot my 273

All the advise is good that everyone has been giving you. If you have never adjusted the valves you should. If the engine has solid lifters it will be noticeable at idle and will be less noticeable at cruising speeds. (I'm sure the stumble is the carburetor). I'm not sure the dying at a stop is the carburetor but could be that or the timing. If it has a stromberg carburetor, throw it away, really! Get a little two barrel holly or a carter. One real easy check is the accelerator pump, it needs to travel below the float setting or an air gap between the gas in the bowl and accelerator pump will cause a stumble. Set the carb. rich it will at least give the engine the vacuum it needs (3 full turns both screws) then adjust it in just until the engine idle speed starts to drop and then back it back off 1/4 turn to 1/2 turn. The timing is initial and mechanical which sometimes is not enough to idle correct so that is when you add the vacuum advance and just add it at max setting first, (this is assuming the canister is adjustable with a 8/32 Allen wrench) then when you drive it it should be very nice at stops and at idle and you should be able to idle the engine down to the throttle plates just barely being open the correct way a carburetor works. And you will also know if the vacuum advance is to much when you cruise it on the highway it will surge if it is too much, then back it off a little. By the way the canister is full vacuum just cracked open 1/4 turn counter clockwise, the more you back it off, the more it backs off. If the engine pings & detonates at acceleration it has too much initial and or mechanical, back it off 2 degrees at a time. The 273 should run pretty darn good with 11 degrees initial, 28 to 30 mechanical. The vacuum is debatable at 35 to 50 degrees. Hope this helps you, we all go through the hoops to get these MoPar's and any other carburetor engine running good. They are all just slighly different, but one in the same!