i noticed in your facebook comment you mentioned about the crank being forged i think, but you seem to suggest it is a stock crank 6G72, have you found out the stock crank is forged by any chance, or have i got the wrong end of the stick. am i right in thinking 6G72 is the 3000GT crank. i am not very good with all the code numbers.
"Head studs are not the same 6a13vs 72/74/75 ... Crank is awesome same like 6G72 ( forged) ...Anyway stock cams , stock valve and no proting heads."