Double the original cost IMO once you had the 6 pots, 18" wheels, front diff, gearbox, suspension
Plus its all the little bits you get raped on, engine mounts, clutch, hydro conversion, aeroquip, poly bushes, ADJ suspension, intercooler, alloy bits, wiring looms, engine management and monitors, fuel pump set up's with extra pumps and swirl pots etc plus all the labour
600BHP is NOT cheap I know and don't even have 500bhp lol