Basically i have an rs 1800 that is in need of a new bit of floor pan. There are 2 holes which have rusted through. One can easily be patched but the other is where one of the bolts for the drivers seat. Obviously i dont want to just do a dodgy patch up on it. My question is:-

Can i just cut the floor pan out of another fiesta and just weld that in?
Does anyone know if i can buy a panel for the floor pan like you can do for mk1 and 2s?
Would the floor pan out of a mk4 or mk5 fiesta fit?

The car is a 1993 mk3 fiesta rs1800. Apart from this rust and around the filler cap the car is clean.