If you had oil in the passenger side hose that would be really bad because it should be drawing fresh air into the motor through the passenger side. I really don’t know if the reduced size will cause any issues, but I just think of it as the crankcase ventilation system inhaling through a cocktail straw.
Something else that might be worth looking into as a PCV valve option, is the valve used on the Thunderbird Super Coupe. I’ve heard that the OEM Motorcraft valve for this application has a built in check valve. I haven’t confirmed this but it might be worth checking into.
Crankcase ventilation air path