I bought a grommet at the local Ford dealer for my '65 352 with the road draft tube back in 2004. It's p/n E7AZ-6A892-A.
In a couple of weeks I plan on going to Mustangs Unlimited and get parts to add a PCV set up. They seem to have all of the parts. I have a diagram of the crankcase vent system. Probably bring my grommet to make sure the PCV valve to hose adapter fits OK.