Wow i guess its time I find another motor,and there is 1 in long beach california complete for sale and its running.
The intake is not a one off first of all and second yes Mikuni's would be the choice,there is a guy called Wolf's creek racing back east but he is a fuckin douche bag to deal with,but good luck.
I heard you can get cranks for them down here in the south bay area not sure were.
There is a website you can get all the info and parts from,called FJ20.com
And congrats on owning the best 4 cylinder motor nissan built,of course other guys will talk shit but the truth does hurt also.