All of these are too small for a 400” motor. But when you run 2 of em they’re about perfect for 200”. The 3071 and 3076 have the same turbine wheel 60-55, the compressor being 5mm larger on the 3076, 53-71 vs 57-76. The 3582 is close but a little larger on both wheels, 68-62 turbine and 61-88 compressor. The decision to stay with a T4 flange will likely push you, (@BoostedLilRe) towards a little larger frame turbo. You can get the turbine for the 3582 in a couple A/Rs I’d lean towards the smaller ones. Like .82 for a street car.
