basically i have no knowledge on the yb so i thought id see if anywon can help

from a completly standard saphire 4x4 cosworth engine what would i need to achieve 450/500bhp i no the gearbox needs upgrading but as regards to block pistons cam sizes head gasket rods ect i basically want a spec to build to but all this group A ect is confusing me i dont no whats good and whats not any ideas would be grately apreciated i'll be running a garret gt30 external wastegate also shud i stay standard bore size,any help would be great