Early B body cars had a metal shroud. Pretty rare to find original ones but they are reproduced. They are heavy and ugly so don't feel like you need to use one though. Since you have an aftermarket radiator you should look it over to see what shroud (if any) it was designed for. Hopefully a late model molded shroud will work. Here is a picture of my '65 Coronet. I've modified things so a late model shroud fits and I installed a clutch fan. I also installed a coolant recovery tank. A late model setup like this should take care of any cooling issues but it does take some work to install.