Blue is basically Red without 3rd gain stage, which is R12 10K cathode resistor. Blue is 3 gain stages so it won't have Red amount of gain, which has 4 gain stages. To have so, You got to boost Blue with a pedal.
Cameron mod is a variation of factory gain mod, being R12 3rd gain stage cathode resistor bypass, so in parallel and not in series with cathode resistor. Factory mod is 2.7K in series with 0.22uF bypassing R12. Cameron Mod is 10K in series with 1uF. R12 stays still 10K with bypass. Cameron mod has less gain than Factory mod.
If You want more gain for Blue You may bypass R19 1K 4th gain stage cathode resistor with .68uF or 1uF cap, as done in classic Plexis. It will give tad more gain in the mids on all lead channels. In plexi mode it gives classic Marshall crunch to dirty clean.
Regards, Andy