Any external leakage should also be taken care of with either grading corrections, curtain drain
or some sort of effective waterproofing.
The basement that exists today, protected by a curtain drain
and a sump pump, was completed soon thereafter, 27 years late.
If you decide on a curtain drain
, stop laying the stones about a foot from the top of the trench, lay a landscape fabric over the stones and top it with a couple of inches of coarse sand.