IMO a thermo would be best for street

when mine is idleing for a while you can hear the fan clutch go in and out with the t stat cycling

for cooling I uped to a 7 blade fan off a amc hornet and put it on a stock thermo fan clutch

I did not have a cooling prob and the temp went down 10*,so I bumped the t stat back up from 160* to a 180*