hehe kool
i've got a 7mgte and planning to prove to the world that we can do it too lol
i do mid 13's at the mo but that was on a bhg engine... have fresh rebuild and got 278rwhp now which is about 30rwhp more than what i had before on 5psi less
the r154 seems to have very different ratios than the w58... i think if you got the jz diff and gearbox your ratios would sort themselves out... but i think first get an r154 and see what your ratios are like... if they're still not suitable try changing the diff
what made you go 1jz?