Regarding the Toploader, for many on this forum, and others like it, including the Mustang Forums, it is the period correct box for Fords between '64 and '73.
Very strong with available parts. In addition, to the wide and close ratio box, David Kee
www.4speedtoploaders.com also sells a Road Race Sebring box that has closer ratios than the 2.32 box. He is the best supplier of these parts in the country. He has components that no one else has (rail kits, lids, speciality gear sets, etc.). He has developed a strong following and could be very helpful with your shifter question. Give him a call.