transit wheels on a 67

[dragn91]

Just picked up two sets of transit wheels I love them. I have a very crusty 67 short step I want to put these wheels on. I would like to use spacers on the factory drum brakes for now then eventually swap the front to disc. I know the 67-68 rears are narrower does anyone know exactly what size spacers I need to run these wheels on a stepside truck. I'm getting tires mounted tomorrow but the rear lugs are completely rusted so I'd like to just cut them off to get the ralley's off and have everything I need on hand to put these wheels on when I do.