Eventually, i'm gonna try out the old Shimano freehub that I brazed. The freehub body part is pretty well stabilized. The weak point may be the toothed interlocking part that engages the hub shell to the freehub body. I pretty much did the same thing as on the 63cx.com site.

With a freewheel, the problem will be that it'll unscrew with backpedalling. Same as a track cog without a lockring.