OK, some preliminary questions:

1) On the first schematic, in the lower left corner, there's a tube pin out shown for a 7BZ? I'm not understanding why it's shown. I thought this preamp used (4) 6AQ5 tubes.

2) Is a 6AQ5-A tube acceptable to use?

3) How does the wiring run from the power supply side (right side) to the audio side (left side)? There must be a bottom or something I cannot see in that middle section where the four tubes are located? And the wiring runs underneath that?

Thanks,
Mark