There were Gen 2 290, 343, and 390 ('66-'70) and Gen 3 304, 360, 401 ('71-'91) engines. The Gen 3 had slightly taller decks, but with only a 9.208 max deck height (Gen 3) were all considered small blocks. (SB Mopar is 9.600) The intakes were slightly different, but could be slightly modified to fit.
But there were no major changes as in the SB-BB Mopars,Chevys, or Fords.