Slant 6 and 904 What's it worth?

I just bought a 69 dart completely untouched never been messed with I'm pulling the slant 6 904 and 7 1/4 rear end and putting in a 440 5 speed 8 3/4 the car runs great!!! has no issues I have a local interested in the slant 6 904 and 7 1/4 i have no idea what these go for im Not trying to get top dollar just something to put towards the BB any input is appreciated