E58 400 plus HP Dart sport build

400 should be no prob for a 360 . I have always run stock distributor with no problems besides the ballast resistor , always had a spare in the glovebox . 5 years ago I went with the FBO ECU , eliminates the ballast and has built in rev limiter , so far no problems
as an aside , never do buy into the mag builds they have bills to pay and guess who pays the bills . They are selling products