Lead will shoot faster than a jacketed bullet with the same charge weights. Lead has less barrel resistance and slips through easier and therefore is quicker.

The problems with lead can be in leading both if the pressure is too low or too high and if you like to spend hours scrubbing out bores then go ahead an push them as hard as you dare. Careful workup is the best way to avoid all problems though it may take some effort and more time.

If you have absolutely no data for lead a good place to start is a 20% reduction less than the max load for jacketed of the same weight. A 10% reduction from that maximum will usually give your the same as maximum load velocity of the jacketed bullet.