If you want the drip tabs then as far as I know no one has them separately as well as the oil fill shield.
You might look for a set of original Boss 302 valve covers that still have them installed?
Someone like Virginia Mustang may have repro Boss 302 covers. If not, you need to make the rounds of the Mustang parts suppliers here.
Go to
www.saacforum.com and post a wanted add for the parts that you want.
There are several people there that I know have the parts that you want but they are not normally sellers.