Judging by the dates your saying that you want, you probably after the TA22.
This model has the wedge shaped front amber indicators in the front panels.
The RA23, which came after that model is harder to find parts for, you can't even get an off the shelf radiator for it.
Engine parts for the single cam engines are really easy to find as after market spares are easily available from auto part stores.
Finding new parts for th twin cam engines is a real cow, but they are a lot more fun to drive and respond much better to modification.
TA22 body parts are probably easier to get 2nd hand than the RA23 ones.
RA28 parts are hard to get, full stop.
If you get a celica from before 1974 you will be allowed to modify it more and not have trouble with ADRs.
For example, if in SA, you wouldn't need to notify motor reg that you'd just put a turbo on it. After that date you would have to get it engineered.