the std head will be fine, but will benfit with a port and a polish and bigger valves
std cams are fine to as they are the same has the rs focus ones but get get zetec turbo's ones from area six and places like that
reconmend vernier pulleys if you go that route also a under pulleys set
can use std rs focus headgasket from ford they are try and tested
will need forged rods and pistons
will need engine management
intercooler,intercooler pipes and hoses
could use rs focus exhaust system set up and exhaust manifold and down pipe or go custom route
will need plugs from a rs focus
and can use the rs focus organic clutch to cope with the power