I'm building a 396" stroker

I personally would go with a cam something in the 245-255 range @ .050 with a 108/116 CL. I think that if you had problems with a 1 3/4 hedder then the 1 5/8 step to 1 7/8 may still give you a pita around the steering. If this is going to be a street only or mostly car then because of the mufflers a 1 5/8 hedder will work just as good as the step without the added hassles IMO. The main restriction is the muffler not the hedder or pipe. Everything else sounds good in the combo.