The T5 shifter position can be changed by using a Chevy S-10 extension housing with the S-10 shift rails. Its a bolt on as long as you stay away from the .80 5th gears. Speedo drive gear may require a shim in some cases(shaft diameter) Picture compares a Camero housing with an S-10 but the Mustang is the same. Beware some S-10 came with electric speedo pick-ups instead of cables.
More info at
http://www.flatheadv8.org/t5-swap.htm