The 10k tach is an early RSR item that I picked up a long time back - when they were only a couple hunderd dollars.
You are correct - it has no redline on the face on the gauge. The engine itself is a short stroke twinplugged 2.6L and would happily rev itself to pieces if I didn't limit it to 7,500 rpm
Next year I'm going to fit 906/RSR cams and have a self-imposed redline of 8k