Re: parts advice
Unless someone has done the exact job it will be hard to tell you precisely what parts you'll need. Obviously a lot will depend on stem diameter and length, head diameter and length, type of bearings that were used on both the bike and the doner motorcycle.
This is going to be a mix and match job and until you have the fork in hand you won't know what you'll need to couple the two pieces.
Maybe there is someone who is familiar with the the Suzuki and can offer some suggestions and they'll chime in. Otherwise, good luck. It sounds like an interesting project. What are you doing for a rear wheel?
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"