so what made you decide to go with a 1gg? ke70 are even better than ae86 in the curb weight and weight distribution department. fitting a big heavy 6 and heavy gearbox in there is only going to ruin this characteristic.
What Purpose is the car going to serve? judging by your avatar i would say drifting so you will find your car is virtually impossible to turn in with that weight over the front wheels.
when it comes down to the conversion more is needed than you may think...
Diff, Gearbox, Tail Shaft, Engine Mounts, radiator, thermo fans AND
Giant hole in firewall/gearbox tunnel(if you hope to retain any of those weight characteristics that make ke70s and ae86s good)
they were never intended to take these engines so most parts will be custom jobs (putting new mounts on F series Diffs custom gearbox cross member etc)
best bet is a 4AGE, simple but effective. it isn't necessary in such light cars but if you really want more torque and power a 3SGE or 3SGTE would be the way to go although it would be as much work as the 1g to get running it would have a nicer weight balance without cutting too much out of your firewall.