best way is 400+bhp and a very fat wallet
personally i've done the expensive way, i'd do the 300bhp way and get an st170 bottom end, strap on a blacktop head with a 1.8mm gasket. then find a good gtx28, frs inlet and tubular exhaust manifold.
run on megasquirt (find mapper first), siemens deka IV injectors, swirl pot in boot and 044 pump.

this is where it gets tricky though, gearbox....
you will destroy an ib5, these zt's are full of torque, don't believe that they aren't.
got to be an mtx75 (mondeo, focus) the frs has an lsd and you will benefit loads from it, but will cost £500-600 for a good one, then there is the clutch, full AP paddle (need to convert to hydraulic pedal setup on top) and they're around £450. then there is custom driveshafts and an electronic speedo needed.....
costs start to spiral i'm afraid, or keep buying cheap ib5 boxes and get good at changing them (1.5hrs start to finish lol!)

oh and you'll need grippy tyres, don't worry about brakes too much, as i found you only need them when you start tipping towards 150mph, then the car lifts off the road a bit anyhow. brakes are for stopping quickly, so the better they are, the later you can brake, standard ones will stop any car, just may need a runway to make it down to 0 safely.

honestly the engine is the easy bit, getting power down and not tearing a box to bits is the expensive bit i assure you.
might be worth adapting some mk6 fiesta struts to fit the mk2 fiesta, then you don't have shaft issues with an mtx box.