Moach your G42 Looks great first of all, looks like you put a lot of work into it!
I noticed in your post's you implemented calculations and tables for air / altitude thrust levels for the ramjets. Im totally new to orbiter dev and dont really want to reinvent the wheel so to speak. I had read an engineer back in 90's proposed using f-15 engines as a stage 0 component, and it sounded plausable.
Well I was thinking S-71 J58 Engines would be even better due to thier turbo/ram combination. Do you think all your work on the G42 ram calculations could help in my design?
Any help would be appreciated.
You can check out my photos for a example pic of them on a falcon 9