Nice work!

I have been working on something similar (not much time lately), I've designed a symmetric inlet flange and put a recess in there to accept 38mm (1 1/2") pipe. My landing for the injectors looks a lot like yours. The 3D printed plastic parts fit pretty good. Making the inlet flange symmetric just means there's an extra mm ish clearance on one of the bolts at the bottom, no big deal considering the way it's fastened. I tightened the clearance on the top bolts to locate off them, two location points means your less prone to tolerance stack up.

The part I haven't gotten sorted out yet is the best way to clamp the fuel rail to the flange plates. I'm also trying to figure out the best overall design to minimise fabrication since that's where I'm likely to make a meal of it.

What CAD package are you using?

I'll come back and stick up a screen grab when I'm on my other computer.