B or RB in A body

I have the Schumacher Tri Y headers on my 70 Dart now, 440. The fit is good with power steering. Going to build a stroker 383 for it in the spring. (438), so may try a set of another type and see if they fit. I have 2 sets laying around. I'll check fitment when I have the motor out. Do regular headers increase power levels over the tri Y headers?