To make sure I understand... are you talking about the lowest rev point between shifts, before clutch engagement?
FWIW... I've found egauges.com (no relation, etc etc) great to work with, and excellent prices - both for gauges and senders, and they carry the full VDO line:
VDO: Cockpit Black Series Gauges: Tachometers - In Dash (electronic) - eGauges.com
Cockpit is the stock gauge style for our cars - though I don't see a tach there that wouldn't look too small...