Slant Six Rocker Bolt

I am needing a special shoulder bolt with a smaller 5/16-18 thread, this bolt holds down the slant six’s rocker arm shaft & is for the hole closest to the firewall, the rest are 7/16 (I believe). Seller must be willing to ship/mail to NC at my expense. Thanks, Erick 9AB9C30E-7638-492A-BEC3-8B705C1BB500.jpeg