HP limit with 1-5/8 headers

Since the headers that I just bought for my 66 Dart 360 project have 1-5/8 primaries and 2-1/2 collectors, what do you think will be the hp limit of the engine? Can I still make 450+? The engine will be more strip oriented with 12:1 compression and eddy heads. I don't know if porting the eddy heads will be limited by the header primaries