Well for 650-750hp.... a 1JZ is gonna take more work to get it to that level than going with a 2jz. Not saying the 1jz isnt capable, it most definitely is and quite under rated. To make a honest 500whp on pump id go with a precision 6262, 264 cams, and AEM with a GOOD tune (of course all supporting mods). Not 650-750whp but thats on pump gas and moderate boost (17-20psi).