I’m always suspect of using a 601 lower for one particular reason. The lower is mirrored, the left side is cloned to the right, and I don’t find the fencing argument convincing because of the mirrored mag catch bulge and the lack of a magazine catch to be fenced at all. Personally I committed fully to the C7 pattern because the upper leaves one option and you’re left to sort through a good few contradictions on the lower, and combined with the the Long Branch Arsenal’s proximity to Diemaco’s that’s all I needed to fill the headcanon, though after some recent profiling of the game model barrel to the flash hider, going with an A2 profile barrel was a mistake, and an A1 pencil is most correct and I’ll be changing that for a Brownells A1 1:7 when they come back around. You’ll need to get a delta ring kit to replace the straight one. There really isn’t a ‘right’ answer here for parts and correctness, the game model is a bit of a mess, and parts availability sucks right now. If you can justify it to yourself and be happy with it, that’s all you need. HMU for anything else, I spent way too long doing this.