IMO – Yes. For the simple reason that you want as little to fail in the future as possible. If there isn’t any end play in the bearings, keep them as spares. If it was me, I’d replace every bearing you could, i.e., steering shaft, tie-rod ends, spindle and king-pin. But it would be a good idea before you start the restoration, take the frame to a kart shop and insure the frame is straight first.