GL1000 front end

Early GL1000 front ends are pretty much a direct swap on CB750's. This gives you dual disc brakes and bigger forks.

Before and after on the GL1000 fork lowers

From Mama Duke 2.0

From Mama Duke 2.0

Painted lower fork legs

From Mama Duke 2.0

There's a little more to it than that, like using the fork tube from the original CB750 front end to push the bearings onto the stem, but for the most part it's a relatively simple operation.