Been there done that as well.

Basically you'll need front and rear axles, prop shaft, petrol tank and fuel pump besides the obvious stuff.

I know of people who used the standard Sierra T9 gearbox and even standard diff but you won't be revving much with those - best switch to Cosworth items as well.

Also I left the standard brake master cylinder but used Cosworth slaves and brakes all round. The size of the master cylinder across the range is standard at 22mm (I think). I didn't bother with ABS.