The 3S flywheels have a different PCD to the 1MZ crank bolt pattern, as shown below:
So you have to elongate the holes with a milling machine, like this. (Just less dodgy ;-) )

You can avoid this process if you buy a 1MZFE flywheel, there are a few aftermarket ones and you might even be able to source one through the wreckers.
If you using an E153 gearbox, you can use a 3SGTE flywheel, pressure plate and friction plate as it all bolts up. If your using an S54 gearbox, you need to use a 3SGTE flywheel with a 3SGTE pressure plate, along with either an uprated 3SGE friction plate (stock will die quickly) or a custom 3SGTE friction plate with a 3SGE spline center in it. This mix and match is because the E153 and S54 have different sized input shaft.
Good news is, I spoke to NPC in Brisbane about 12-18 mths ago for this exact custom clutch setup. They can do a nice Heavy Duty Sports Organic clutch that will handle 250+HP and 300+Nm with the modified center for ~$550.
A capable auto electrician should be able to do the wiring conversion, talk to Vinny on here (username: Vinnny), he did his V6 conversion in his SW20 himself and drop the wiring side into an auto leccy and it was done pretty well from what I remember.