DMTR's are vac secondary's , the DFT is mechanical so for track use use the DFT, just make sure the DFT is the larger size, there is a smaller one fitted to the 78-82 fiesta 1300, with 22/22mm choke sizes, the mk1 xr2, the escort mk3 xr3 used the larger 24/25mm chokes.
The DMTR is inferior in pure bhp terms, it is a economy carb for good emissions, the DFT is a very good carb.
tabetha