No clue on the chevy fitting the datsun,(chevys have always kind of had an aversion to me, and I was never much interested in them either)
My guess would be not only no, but severe no. Usually the tranny co's work with the manufacturers to try to gin up some changes so nothing interchanges, so ya have to buy every part through them. American ingenuity at it's finest.

Ya say the engine is tired?? mine isn't. Want it?? Or are you gonna take a shortcut and drop a relatively fresh v8 and tranny....and be cheaper in the process...

 

I'd take yours if its an L engine and your giving it away, other then that I'm rebuilding mine. and yes I said tired its got 200K miles on it and I can tell its gotten a little weaker