as a carpenter iwas able to implement man y forming systems invoving re-inforced concrete fron the exterior walls to minimize disruption. inevitably the wwork was completed, but extremely labour intensive.good luck. watch out for mud....i found many souveneirs as the house was built in 1875. the walls were constructed of clay brick on no footing ...i proceeded with an excavation in 20 foot runs to approximately 18 inches below the firstcourse of brick(6 feet below grade)and proceeded with forming a grade beam with rebar dowels to secure the new knee wall. With the brick foundation i felt like a dentist fixing cavities in removing decayed brick. it was critical to use non shrinking grout to stabilize the repairs on sub grade materials as well to ensure the rebar was all tied to the new wall system. this took 2 years at home... and im still married.