How neccesary are fan shrouds?

Mild 440 with A/C, a new (aftermarket) 4 row brass radiator and a new (aftermarket) flex-fan. The thermostat is a 165. Am I asking for trouble if I don't put a shroud on it? And... did anyone fabricate their own? Any pics or info would be great.

1969 Dodge Super Bee Hardtop 2007 Nissan Altima 3.5SE