I haven't but I am very interested in your results should you get some.
If you need o-rings for the valve covers avoid the stealership. The dealerships around here want $9 each.
I used the viton rubber valve seals on my recent rebuild but not many hours on engine to validate their longevity.....
In this post I replaced o-rings on my second TW. Info might prove useful to you.
Hmmm....I thought Flurosilicone did well with fuel?...oh well.I took some of the o-rings to Fastenal,the guy there was not much help?.....keep tryin!!!.