At the very least, drop the pan for a look-see, and adjust the bands; gunk in the pan makes it a core for me, and the asking price would need to be adjusted accordingly.
Replace filter, seals and fluid also. Unless beat on mercilessly the clutches on a small block 727 will not be worn appreciably in 2 or 3 hundred thousand miles. If you will be doing water burn outs get the bolt in sprag.