Different filament size for the M2?

[Woofpickle]

I have a bunch of 3mm filament that I need to use up before I can change completely over to 1.75mm filament and not feel guilty about the two five pound spools of 3mm PLA that I have sitting on my shelf, not to mention an obnoxious amount of ABS chubs.

I already have several 3mm hot ends purchased and assembled (from MakerGear of course, ever since that nonsense with the Mk3 extruder from MBI I've never looked back!). But I have no extruder block that is appropriate! Is there a 3mm extruder assembly that uses all the same hardware, and matches up properly to the fans? I've been looking at the 1.75 mm build and kind of eyeballing it, and it seems like the only thing that would need to change is the hole size.

I am assuming that the SCAD file on github is easily the answer to this problem, but I'm not sure which of the magical lines I need to edit in order to have it spit out what I want! (I've actually tried to learn how to use openscad on several occasions, but it just doesn't "click" as it were...) What should I change to get the result I want? 

Don't misunderstand, I absolutely adore the way 1.75mm filament behaves, and once I use up all the 3mm that I have, I intend to replenish my stock with 1.75mm! 

Thanks!