The original plugs were Autolite BF42 with a Gap of .034". If the Plugs are no longer available from Parts Suppliers, they can easily be found on eBay. Plug wires can be found through various Mustang Parts Suppliers; NPD, VA Mustang, etc.
The Dwell angle of the Points should be from 26 - 29 degrees and the Timing set to 6 degrees Before Top Dead Center (always set the Points before adjusting the Timing).
Idle Speed depends on your Transmission; Manual 575 RPM and 475 for Automatics; both of these speeds may vary slightly depending on the health of your engine and / or any modifications that may have been made.
Ray