I have an old x2 head too & was planning on doing the same thing with it but the biggest problem with R8 is you can't pass anything through the spindle.
I've considered doing Hoss' mod & putting a 5C spindle in place of the R8 ..
A little more work, but a much nicer finished product ..
Another drawback is that you can't mount it facing up like a Rotary table.
Decisions, Decisions, Decisions!
What ever you do be sure to post lots of pics ...