I don't know how safe this procedure was but it seemed and looked alright to me. When I bought my first 1st gen Camaro, a 1967 RS, back in 1988 from the original owner he was tall and needed extra driver's seat travel. He bolted two flat steel pieces about 15-18 inches long and 2 inches wide to the seat holes in the floor. Then he welded on 2 uprights each to these steel pieces and attached the seat tracks to these. This gave him I would say another 4-6 inches of travel rearward. I am short but was able to drive the car from his place to mine with the seats as far forward as they could go. Since I didn't need this extra length I removed the steel pieces and bolted the seats back onto the floor as originally designed. Unfortunately I didn't take any photos of this homemade adjustment.