As you can see in my #18 post… I welded it… or better…. I asked to a Titanium bike welder (Rewel) to do it!😁
You could see the adapter welded to the frame in the picture. And he did a great job IMHO.
this one:
https://www.assolutions.ca/shop/adapters/flat-mount-adapter-for-is-frame/
I saw that it's out of stock, but if you want I may have one more...
In the picture you could see the clearance with a 35c tyre. With Pirelli 40c gravel M tyre (that measures 42 on my rims) it’s about 6mm on top and 14mm on every side.
In origin I had a 135mm stem, with flat bar. I have a 110mn stem too, but I still prefer this 120. It’s a 0 degree stem and so the length is less than a -6 standard stem…
Here is my fool Gravel conversion of a Litespeed Ocoee I bought in december '94.
In 2018 I destroyed my last suspension fork (an old sid modified to have 60mm travel).
And so fork has been replaced with a Whisky part n°9 Cx carbon fork. and the 26' wheels with new 700c Mavic wheels...
After...
If you are still looking, I have a Ritchey ProLite (not wcs) cut at 540mm in grey color, in good conditions (not perfect), and I could sell it for 15 euros...
If you want I could send you some photos.