If you want HI-QUALITY free reverb then look for SIR. I have the famous Lexicon 480L/PCM91/PCM81 IRs used on 80ies (Jarre used it).
However you will need a fast computer.
I generally use a bad reverbs for test and on mixdown I use SIR.
IR consists of sampling reverb (real ones or hardware reverb).
Lexicon are professional hardware reverbs that were very expensive at the time.
http://www.knufinke.de/sir/index_en.html