I have a Celica as well, including my SVX.

Make sure the engine you are getting hasn't been sitting outside in the rain, and make sure it hasn't been sitting with fluids indie of it. Make sure the fluids have been dumped out of it.

If you don't mind spending money, "Jasper Engines" sells remanufactured with 36,000 miles 3yr warranties on their engines and they have plenty of Toyota. Getting an engine from a scrap yard always has it chances of being bad and full of rust if they haven't been used. It's also a good idea when pulling an engine out of a scrap car that you change all the belts: timing and serpentine. And re seal the oil pan, valve cover, and head gasket.

From expierence I know it's quite invigerating to put Celica engines in. I've replaced two 5sfe in my Celica. Until I finally put a 3sgte (2.0L Turbo) in it which I feel is the best engine that yamaha ever made.

I would also suggest changing the whole engine and not just the short block if you are going to replace something.

In my opinion the best thing to do with your engine would be keep it. Bore it out and put some iron or steel cylinder sleeves in it, and replace the rod bearings to TOGA rod bearings which are alot stronger than the factory ones. Summitracing actually builds a rebuild kit for the 5sfe, 3sgte, 4afe, and the 7afe.