Charlie - Dont underestimate the 3sge AND the st162- its REALLY good motor, and car - one of the best 2 litre's out there and renouned for being one of the best FWD cars ever produced in handling aspects .. They respond very well to things like exhaust upgrades, suspension tweaks and so on - which in my oppinion would be a good bet for you to persue till your off your P plates ( insurance sucks ass - believe me ! )
Any of the good jap dismantlers like toyrolla SHOULD have replacement motors you can drop in - though asking the melbourne guys would be best - seeing im a country bumpkin ( who owns the big brother 3sgte Gt4 ! )
Save your dollars - track down a reco or low KM 3s-ge that bolts in - and when insurance is alot cheaper for you - hold off the full hog 3sgte swap OR if you your wise - Buy a Gt4.
They are cheap now - and are good machines .. They might not be as lively as a FWD 3sgte in a car like yours, but the grip side of things cannot be matched with a FWD car - and are really a GT of name and nature ..
Having been in a st184 ( CeLiCa's Coupe, group A St185 motor) i was mightily impressed by the way it accellerates, It would Kill my car "as is" over a quarter mile - but to be honest for a few milliseconds difference in accelleration and a slight reduction of power to wheels figures - Id much prefer that power delivered thru all 4's - not just the fronts. I can happily drive my car in the wet and have minimal issues with slippage ( unless full boost kicks in and it decides to play crabwalks on me ) whereas a front wheel drive turbo would require a VERY gentle hand to control it in wet conditions.
If you want mad FWD traction issues - got the front wheel drive 3sgte swap - if you want the boost AND the grip to back it up - go the Gt4 !
If you have any questions re the Gt4 - ill be happy to share oppinions - as im sure CeLicCa will on his Front WD celica.