Electoral system for national legislature

Reforming Electoral Systems in Mexico, Horcasitas and Weldon, in Shugart and Wattenberg, Mixed Member Electoral Systems, OUP 2001, pp209-230 (esp. table pp228-229)

If the highest polling party wins less than 35%, pure MMP.  If it polls over 35%, it gains bonus seats to enable an assured majority.  No party can win more than 350 (70%) of seats.  For other parties, MMP if highest polling party has less than 35%, parallel if not.

300 FPTP: 200 List PR using closed list and largest remainder