The usual stuff with Sierra's, not just Cosworth. Brake discs, front track control arm bushings. However, head gasket was blown when I bought it. Possibly too much boost.
This car is a bit dated compared to the Evo's and Subaru's of today, but still kicks their ass... on a straight line anyway. My one is stage 3 tuned and puts out about 380bhp. UNBELIEVEABLE power. the 4x4 really suits this kinda power, as it doesn't fishtail like the RWD models. I've chewed Skylines, Scooby's, Evo's with this. A 325i is only tarmac fodder to this car.
However, if you have a modded version of this car, be prepared to walk home if you roast it on a regular basis. The most reliable option is to get a standard one, although I couldn't go back to standard now.
I agree your car would be very very fast, faster than any standard scooby evo or skyline. Hower have you considerd the sort of power you can get from these newer japanese cars? Skylines run into the 1000+ bhp power levels! Then take a standard cossie, and a standard 04 UK scooby, the scooby won't kill it, but it will beat it, to 60 and 100 but not top end. And evo's? What can I say, the best car you can get as standard.