Need '73 Mustang steering help

73 Mustang convertible, 351C w/pwr steering. Recently bought the beast and it has a problem with returning the steering wheel back to the center after slight adjustments down the road or turning a corner. Same problem in both turning directions. No excessive play in the steering wheel. Turn left, car continues left turn until you make corrective action and turn a little right...car continues right. It's like driving down the road bouncing off the edge and centerline paint stripes. Recommendations on corrective actions or which parts to replace?

hmmmm sounds like worn our ball joints. might wanna check them