To get it back on track - there's some great stuff on Reeve's page
http://www.reevesaudio.com/studiothree.html
Some great photos of the old gear and a schematic, simple as it was. They mention the Pultec setup they had and some info on how all that was wired up... - a pic from that page:
There's a section on that page:
"The Daven pots provided calibrated attenuation to the meters in 1 decibel steps to allow adjustments to an average program level to be set to "0"dbVU and a reference for calibration to the recording deck was thereby achieved. It allowed you to get closer to absolute "0" level of the console's buss which is common in today's digital "Brick Wall" threshold. At this point the volume control of the tape deck would be re adjusted to match the recalibrated meters."