Need Advice [ 65 Dart Build-up ]

Hello, Gents Im currently building a 65 Dart GT and I need lots of advice lets start with the motor I want to build either the 512 - 400 B Stroker or the 534 -440 RB stroker I have heard about fitment issues for the reason to use low-deck 400 what are your thoughts about this issue ? I have [2] good virgin 440 engines with the [ 4006630-440-3 ] casting number and then the 4006530 - 400 block please tell me the advantages of using either . I plan on running heavily ported 906 heads with top quality parts hyd roller victor intake [4150 ] and would love to run up to 250 NOS kit . I don't see as much info listed about fitment details with the early Darts I plan on using fenderwell headers - thanks Chris