FMJ-bodies use the same engine mounts as late A-bodies, and late B-bodies. A straight swap is fairly easy for the Gen3 Hemi, Schumacher engine mounts http://www.manciniracing.com/tti57hestenm.html, will bolt the engine to the K-member, Hooker and TTI http://www.ttiexhaust.com/Category-ClassicHeaders/Subcategory/ccGenIII.htm make swap headers, and Milodon makes oil pans. The Gen3 uses an LA-engine bell housing patern. The flexplate is available form a number of sources too. The hardest part is controling the engine.