904 freshening ?

While I agree with the last couple of posts that 8 1/2 years is a long time for a transmission to sit... I would install the engine and transmission "as is" for a few of reasons. 1) it is very easy to pull the transmission out of a 66 dart. 2) transmissions are not designed to be pulled apart several times. 3) it is alot easier to troubleshoot a transmission in the car than on a bench in a bunch of pieces. I have a transmission dyno at work and it is easier to install a transmission in a 66 dart than on the dyno.
4) I "fixed up" an old chevelle that was sitting in field for 12 years and never had any transmission internal sealing issues (I did explode the lo-roller clutch after installing a bigger engine and shift kit). 5) If you carry your trans into a rebuild shop, there is no way for them to test the transmission either. All they would be able to do is clean and rebuild the trans... any problems with the geatrain, bearings, valvebody will most likely be overlooked. For this reason, I never guaranteed any transmission that was carried in.