help what do I need to change or look for

63 push button trans has to go this push button trans is gone.it is a 225 eng .I am going to find a newer /6 trans and put it in. There is somthing about this 225 63 model motor and putting a newer one on it. I will pick up a new converter for the newer trans but I am not sure what I need,It has somthing to do with the splines or flex plate, not sure yet..posibly a different trans mount, not sure yet .So I will be looking threw some thead's.thank you for any insite on this tran's problem. Mike :book: :salut:

63 dash pic resized.jpg