I was thinking about room on the floorboard to accommodate both the Mitchell shift handle and the plate to access the dipstick. Do they overlap, i.e., does the metal plate have to be cut to accommodate the Mitchell shift level?
I am not sure where your transmission dip stick is. Mine is off the starboard side of the transmission and replaces the normal pipe plug. So the plate to access the dip stick is on the passenger side of the floorboard. The control for my Mitchell overdrive is in the center of the car in back of the normal gear shift column. Not near each other.