At least some Edlebrock produced 750s use the same booster as the smaller carb - which is too short - and doesn't end at the proper location in the venturi for maximum signal.
So they will be slower to get onto mains than the should etc.
That said, even so, that's not causing what you describe. If it was that serious of a problem they would have had to change it to the right length. So its just a weakness in those carbs.
Initial timing and timing off idle will depend alot on the cylinder heads, compression, engine size, and cam timing.
Use these to ballpark your starting point.
Distributor starting point for a curve
Keep in mind that a pre-emissions era 4-bbl 273 had a factory initial of 10* BTDC.
A more radical cam, lower compression, and less efficient head at low rpm will require more lead time to build the pressure.
What happens off-idle depends entirely on the advance curve. Unless you have an original distributor with a part number tag on it, there's no way to even guess what the curve is. It has to measured. You'll need a timing light, a tach, and some marking on the damper that shows up to 40*. (that is unless you know someone with a distributor machine).
Don't worry about limiting the advance curve for the moment. Just get the initial and see how it runs at lower rpms normal use.
Then figure out what the curve and max advance is, and deal with limiting if needed.
One minor restriction -
do not go wide open throttle without knowing the max timing will stay in a reasonably safe zone.
* If you're going to the drag strip, then you have to make checking the fully advanced timing a priority. Mopar performance recommended 35* by 3000 rpm for stock LA heads as a starting point. If it pings, get out of the throttle and reduce the timing 2 - 3*
