my 451 combo

i am ready to buy my converter for this engine ,on the information i have given,what converter should i buy,i am buying an off the shelf converter from mancini,so either a coan,a tci or the turbo brand what ever that is,cause i live in australia i dont want to get one custom made so it has to be one that is listed on the mancini website,personally i am thinking a 3800 10 inch,what should i buy as i,m ready to place my next order with them?