Notice the volume control hookup. If the volume control is located remotely it is not desirable to ground the low side of the control to the chassis at the remote point. This can lead to ground loops. Instead, carry the ground with the shield of the miniature coax, and from the control to the next stage on the shield of that same piece of coax. This ground loop problem is very easy to control in a modular setup like this. You can mount the boards on pieces of bakelite or plastic when necessary and have full control of the ground situation without any radical rebuild.

Notice that the output is bypassed for both rf and audio (C5 and C10). Also notice C9. This capacitor can roll off the high-frequency audio components. That little transformer is quite efficient out to 70 khz or more, and there is no need for response above about 2.5 khz. In fact, if you use a .05 mfd capacitor at C9, you will have a definite peak around 1 khz that is helpful for CW work, but still results in useable ssb performance. Again, the bfo voltage is brought in with RG-174/U coax. With a high-gain IF strip, it may be helpful to locate the bfo well away from the strip - or shield it.

...Slightly more gain will result if C2 is paralleled with an audio bypass capacitor,...

The circuit in Fig. 6 can also be used as a synchrodyne detector. Tune L1 to the operating frequency, add an audio filter to the output and use a high-gain audio amplifier. You now have a simple, direct-conversion receiver."