493 carburetor tuning question

Leave the pump shot lever spring alone.
See what accelerator pump cam is installed. They are color coded so you won't have to remove it to read the number.

However that said, its best to make sure the off idle is responding well with slower opening of the throttle. Begin with as slow as possible, then try it with more nromal but not jabbing.
It should respond smoothly with no hesitations or hiccups.

Make small changes in initial throttle position, timing, and idle mix. Keep notes of each change you make and whether it improves the idle and off idle power or not.

First, I would make note of how many turns of the idle speed screw it takes to open the throttles so .020" of transfer slot are exposed. Then how many turns to open them so .040" are exposed underneath. Write those down and you'll always know how much the transfer slots have been exposed. Outside of that range it is likely to have a flat spot or a delay.

I'd work with timing next. Measure the rpm and the timing. You can use timing as well as the throttle position to increase vacuum and rpm. So now is a good time to find out where the timing is, and also maybe check timing at 200 rpm intervals so you have some sense of the advance curve in the lower rpm ranges.

If you ever wondered what tuning was, this is it!
Its a lot different than setting it to factory specs type tuning!
Idle and off idle can be the more challenging than some people bargained for, but its really a matter of willingness to iteratively make changes and check results.