Wheel Help Question

[Bert W]

Hey Guys, I put some late model six lug wheels on the 68. I sanded and painted, and added some new shoes. I think they turned out nice. I bought some of the after market center hubcaps. The attachment screws that came with the set are to small. What is the correct size bolt for the wheels? I seem to remember the originals having a taper on the end similar to a body panel screw. Where can I find the right ones? Thanks in advance for the help!