For a 340, you need a JW Flywheel 93009-LC - $270 and a JW Crank Adapter 80012 - $80. The LC is lightweight. There is a heavier version which I think is just -C. The converter needs about 6.5" spacing (varies) and is normally built at 6.0". FTI built mine with 6.25 spacing and sent .25" spacers with it.