Unfortunantly, engine swaps are not as easy on the Toyotas as they are on the Hondas - was a big Honda fan for several years before I moved onto Toyota. Choice of swaps depends on your area - what rules/regulations they have regarding engine swaps and legality of them. Usually safest to stick with current motors - emissions standpoint. But possible swaps, legal or otherwise, that have been done to an 8th gen Corolla include:
1ZZ-FE (1998-1999 Corolla non VVT-i)
1ZZ-FE (2000-2002 Corolla, 2003+ Corolla/Matrix all with VVT-i)
1ZZ-FED (7th gen Celica GT with VVT-i)
2ZZ-GE (7th gen Celica GT-S, Corolla/Matrix XRS all with VVTL-i)
3ZZ-FE (overseas Avenis model)
3S-GE (Beams - Altezza, Celica, Corona and MR2 - single and dual VVT-i)
3S-GTE (Celica and MR2 - factory turbocharged)
4AGE (both 16v and 20v variants)
4A-GZE (older Corolla and MR2 - factory supercharged)
Unless you jump on one of the factory forced induction jobs or build up the current engine to run forced induction - 50 shot of nitrous (I take it is not 50cc but 50HP) would be the better performer than most any of the above swaps. I would recommend against a swap, unless the engine in it is already toast. The 1ZZ-FE in it already pretty much tweaked from the factory - not much hidden potential locked in there, that bolt ons would helpout on - minus forced induction or nitrous. Hopefully you kept the old exhaust mainfold as well - dyno runs have shown that the factory exhaust system with proper porting flows better than any of the manufactured aftermarket ones.
If you are totally set on big HP gains - can't beat the 3S-GTE - a legendary Toyota motor that makes huge power gains. Several built-up engines that push 500WHP-800WHP on a dyno. Sometimes clled the little brother to the 2JZ-GTE engine in the MK4 Toyota Supra - the ones that people have gotten up to 1500+WHP! For N/A goodness - 2ZZ-GE is hard to beat. With VVTL-i - you get a Toyota engine behaves very similarly to the Honda i-VTEC ones (both engines are valve phasing, cam changing), but with a more pronounced switch-over point when the bigger cam comes on. That is 180HP at the crank OEM and redlines at a touch over 8200RPMs (Celica GT-S/Matrix XRS ones) and with an upgraded valve springs - can run up to 12,000 RPMs - dyno verified to make around 230WHP, about 270HP at the crank.