On a second thought...Would it be easier for the arm to be modified to accept a threaded balljoint,and the hole in the knuckle where the ball joint is, fitted with a plug that has a tapered hole in it? This would allow many more options.....Or,a stud welded in the arm,and a uniball fitted into the hole in the knuckle.....Then again,how would the uniball be attached in the knuckle....
Just thinking....
Hoodlum