I just installed a PCV in my 1955 235. I turned an aluminum plug to plug the down draft hole and made it able to accept a PCV grommet from a mid 70s GMC van. As long as you have the baffle/shield in the block where the tube went you shouldn't have any problems. I ran the same PCV for the mid 70s van and ran the hose around the back of the engine to a fitting in the intake. Haven't had any problems so far and it seems to work great.
