Using an online calculator for an 8 ohm speaker and I set the hz at 10Khz it says I need a cap that is 2.0 microfarads. So are you saying I should just hook that to where the HF leads come off the crossover? or are you saying that It needs to be plugged into the middle of the crossover somewhere? Or before the crossover?
I got a line on a pair of used Arum Cantu G1's They look and sound much more like what I should use. I'm probably gonna jump on them.
The problem with just going off the HF taps on the XO is that signal has been attenuated to match the LF driver's sensitivity.

In the name of simplicity and keeping your XO's unaltered i'd probably just opt for tying in before the XO.

2.0 uF in series with the + sounds like a good starting point to me.

In terms of sensitivity, the G1 is probably going to be the better match. However, it is sensitive enough that it takes us a couple db past ideal and could actually need an L-pad to be able to back it off slightly when you get to final tweaking, or depending on how many db the XO attenuates the HF you might end up tying in at the HF taps after all.

The Aurums are really nice ribbons. You'll find them used in several high end/expensive systems. Be careful with them. None of us want to read about a broken one.