correct i forgot to mention about core plugs well remembered , silvertop or blacktop will do 500bhp on a standard block with standard crank all thats needed is good shells , arp bolts and a good set of forged pistons and h beam rods .
i would contact ian howell at area six for the custom built arias or cp pistons as these are made specially for him and have litlle extras , they are around £1300 for a set but you pay for what you get and this will be good for 570+ bhp as in paul johnsons focus . mine runs a standard block and crank and made 522bhp hence the name

cheers paul