Cooling help?

Hey guys. I have a 1969 Dodge dart swinger with a 340 in it. I've been having cooling problems but I suspect that it is due to fact I don't have a shroud and thermostat. Any suggestions on a thermostat that would fit the neck of an air gap edelbrock intake #7576 and what temp to get? Also, I have a 15" flex fan (pic) and a 22" x 18" radiator. Any ideas what fan shroud I should get or how to go about finding one? I've tried the google searching. Should I stick w the flex fan or get another one? Any help would be greatly appreciated. Thank you.

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