If I had a 5 door fiesta and had to mod it this is what I'd do:

2.0 litre Zetec on throttle bodies
15 inch steel rims covering BIG brakes

Streetsleeper

Check your local Loot, FreeAds etc. Me and a mate bought an XR2 from an advert on the wall in Safeways for £50, needs a bit of welding but once we'd cleaned the carbs out the engine was running sweet mind you, that was 6 months ago and its stayed in his garage ever since even still got a set of 88 spec recaros on xr2 runners waiting to go in it