"Obtain" a bill of sale for the motor and a separate bill of sale for the frame. At one time, a single seller could sell you both items, but now the DMVs are looking at this as a "complete" bike and refer you for a bonded title. So two bills of sale from two different sellers. Take both documents to the DMV. They don't have to be notorized or on official forms. Tell them you want to title & register an antique motorcycle. Should be no problem, unless your DMV is not familiar with the process. You will also need to assess the bike with the County Tax Assessor and obtain insurance before going to the DMV.
OR
You can do a bonded title which averages around $150.
Regards,
Rider