Standard Silvertop oil pump is a risk at that sort of power, ticking time bomb over 400 bhp in my opinion! Keep a bit lower power wise and would be fine.

Unless you force a load of boost down its throat I think you would have to port the head as well. Also an MT75 is a weak gearbox that's well beyond its power limit at that stage. You need a T5 ideally.

A standard Focus RS clutch wouldn't hold up either, you would need paddle and they cost loads, so worth considering a Cossie style Zetec flywheel so you can fit the cheaper Cossie paddle clutches.