OK to Use???

I have a 727 reverse pattern transmission that has been stored for the last 25 years

Believe it or not, i just did exactly this more or less..... While i have to say, I agree with AJ/FormS 100 percent.... I have a 727 with an old TransAction RVB, sitting since 2003 with 40 1/4 mile runs on it.... We put in a bracket car and ran it 20 more 1/4 mile runs @ 12.5/110...... no leaks, no drips, no errors lol. A testament to decent construction I'm sure. If I were you, I would at least roll it around to get everything wet with trans fluid again to soak the internals, if you dont plan to have a look at it internally.