Hey there @GlebeHobo ,
Getting hold of an 850R wagon is becoming more difficult, finding a good one is damn near impossible and even rough ones are beginning to demand a premium price.
A V70T5 is a very close substitute with lots carried over, and the same power output (whereas the 850T5 was a little detuned from the 850R).
I wouldn't consider a non-turbo car for a project base - at a bare minimum, you could consider an LPT car.
While, personally, I think that 850Rs have become overpriced for what you'll get for your money these days and while I'd really love a T5R, these are very overpriced now.
In my current case, I settled on a V70T5 as the basis for a project (I've had a few now) and will end up with a convincing UK/French spec FWD V70R by the time I'm done (with a few differences - wheels, suspension, brakes). I really didnt want an AWD car and Australia never got any FWD P80 V70Rs.