What museum are you going to display that BW in? Surely, you are not going to ride it through dirt, mud and bugs, are you?
My intent to photographically document the Tri-Z conversion on Cliff's #2 ended up alongside my New Year's resolutions. However, some salient points are thus:
1.) The triple clamps bolt up without any modification. I just use the opportunity to replace the loose ball bearings on the top with a tapered bearing.
2.) The BW wheel will bolt up to the Tri-Z hub. You will need a Tri-Z axle, since the Z axle threads into the bottom of the fork tube (which is a smaller diameter hole than the nut used on the BW) The '85 and '86 Z axle are interchangeable.
3.) The non-brake side axle spacer from the BW will work on the Z axle. However, You will need a Z spacer on the brake-side for the conversion. The BW doesn't use one at all on the brake side.
4.) The easiest way to get the front brake operational is with a Tri-Z caliper. Sure, they are quarter of a century-old, single pot, three wheeler brakes, but they bolt right up and can be used without any fabrication.
This is a link to a machinist who put a disc on the rear of his XT225. It might be of some interest.