Welcome to the forums. I just did a bit of searching on the net for you and found out that the offset for standard MR2 wheels is 39mm. Unfortunately I couldn't find what the offset is for an 83' Tercel. If you can find out what the offset is for your standard Tercel SR5 wheels then you'll be able to find out if they'll fit with no problems. If you're having a hard time finding out, then try having a look on the inside of the rim as it may be stamped there. If not, then you can easily measure it yourself by taking the wheel off.
As far as I know, they're both 4x100, so they'll fit in that regard, but if the offset is greatly different then you'll experience problems with rubbing and/or clearance. Once you've found out the offset for your current wheels, head along to this site and use the calculators to find out what the differences will be:
http://www.carbibles.com/tyre_bible_pg4.html
It might pay to create a thread in the Tercel section of this site in case anyone has had experience in fitting MR2 wheels to your car.
Best of luck