Magnum 360/904 swap again

Hi there from the UK,my 1st post,been visiting your forum as a guest for the last couple of months reading posts with interest,thought its about time i got involved,i am currently in the process of a magnum conversion in place of 318/904,have searched posts regarding this swap,agood few hours reading,have one problem regarding flexplate to 904 convertor,i beleive B&M no longer stock the magnum/904 flexplate,is that correct,cant see it on the web site,whats the next best fix for this problem,car is a australian chrysler valiant charger A-body platform.
Many Thanks
Terry