This is NOT an easy modification, but can be achieved.
NB: these tips are given as my opinion and every aspect of an installation of this nature should be checked carefully. DO NOT rely solely on the information given here.
3SGE rated @ 150-180hp stock (c/o Matti)
This is by far the easier of the 2 engines.

OILING

Replace sump and oil pickup with pieces off 1S or 2S motor (ex Aussie & European ST140 &ST141 Corona RWD circa 1982-85). This takes care of the slanted sump on the FWD 3SGE. Note that you may? Still experience problems with oiling, as the 3SGE motor normally slants about 15-20 degrees and in an upright position does not drain the oil back from the head as well as it should. I added about 1" to the depth of the sump and oil pickup to hold extra oil and ensure adequate oil remained in the sump. I also put a baffle in the middle of the Sump to fix problems with the oil rushing away from the pickup under acceleration.

MOUNTS

Use 1S or 2S mounts as a BASIS for your new mounts. You will very probably have to move your current mounts and fabricate/reweld.

GEARBOX (A number of options are available.)

Option 1 (for 3SGE ONLY! )
Use complete bellhousing, 6 bolt flywheel, companion plate, clutch, pressure plate, starter motor and W55? gearbox off 2S RWD motors. W55 box and Bell housing off 2C RWD will also fit perfectly as they both use the same bellhousing (#31111-22120) 2C & 2S W55 box should be strong enough for this motor. I would tend to purchase the driveshaft yoke at the same time although any standard yoke should fit. Use a Pilot bearing off a 2S (or 18R/RG. It's a pretty standard Toyota size, probably cheaper from a bearing dealer than Toyota.

Option 2(more difficult but a better option if you plan to "wind" up the power on 3SGTE)

Use a W57/58 Supra box. This requires a 2C\2S bellhousing, 2C starter motor, 2C or 2S (better) companion plate, original flywheel, clutch, pressure plate off 3SGE. This MAY require an adaptor to be made between the bellhousing and the gearbox. I know for sure the 2C/2S bellhousing fits, but I accidently purchased a R154 Supra box (off 7MGTE) and it is somewhat bigger than normal and DEFINITELY needs a 28mm thick adaptor made between housing and box.. The W57/58 may not. The Supra boxes will also push your gearlever back about 4-6" requiring some surgery to the floor. (R154)Get the driveshaft yoke when you get the box as it IS bigger than most of the standard Toyota ones. Also, I'm using the clutch fork and release bearing from the 3SGTE geabox and the Pivot from the 2C Bell housing. Cant yet report if this works, but it should! As for the ringgear, if you are using the original 3S flywheel, you will need to remove this from the flywheel and turn it around and remount it so the beveled teeth face the front of the motor, which is where your starter will now be. I'm using the 2C reduction type starter. Use same pilot bearing as above.

FLYWHEEL

You cannot use the 2S or 2C flywheel on the 3SGTE as it has 8 bolts instead of the 3SGEs 6 bolts.

SUNDRY

You are faced with a few other problems. The dizzy on these motors will now try to punch a hole in the firewall (as will the rear radiator outlet) and you will either need to ..(a) adapt the dizzy to face 90 degrees (b) use dizzy base as crank angle sensor ( c) use a crank trigger. You will need to adapt the rear radiator outlet to do a quick 90 degree turn as it comes off the block and put your sensors in the water flow elsewhere. You'll need to run a long hose from this outlet to the radiator. Plus all the usual problems off new accelerator linkages, wiring , exhaust. Be aware where you crossmember is as the S motors have their sump at the front.

FUEL

Provided you have a car with EFI already, no real problems (that I know of). If not, you need to add a fuel return line to the tank and add a high pressure (40 odd lbs) pump and filters.

3SGTE rated @ 200-255hp stock (c/o Matti)

OILING as for 3SGE. I intend to add an Oil Cooler MOUNTS as for 3SGE GEARBOX ..now your problems begin... You can use the same gearbox combos as above BUT I think the Supra is the best bet if you intend to raise the output of the motor. One other VERY MAJOR problem. You now have turbo charger mounting brackets and drain hose right where the starter wants to go. Options??
(1) Give up. (2) Choose easier transplant. (3) Move turbo charger (not a very good option IMHO. (4) Modify bell housing (remember, you may still need to adapt to gearbox) (5) Have custom bellhousing made with starter on RH side. (My option)
This particular problem shows the importance of planning ahead.(DUH) You MAY be able to make a starter fit on the LH side as the objects in the way are the oil drain and Turbo mount. I still wouldnt like to see a starter that close to the turbo as I'm sure the heat would "cook" the starter.

SUNDRY

As for 3SGE, but added height of inlet manifold and probably need for intercooler (I will probably go for an air-water version) will require surgery to the bonnet. At this stage a heavier diff is called for also IMHO. FUEL as for 3SGE.

FWIW...find an easier transplant.

Original by: Roadrunner@clear.net.nz (NOT part of Australia but a near neighbour)