i have owned some 10 or so Austin Mini Coopers, and here in Florida always had a overheating problem with those radiators small as heater cores. My "solution" was to go to NAPA or Oreilly and search/look in their books until i found the size/shape/outlet i wanted, and then plumbed that Heater Core into the stern of my mini's, running a 1/2in copper tubing back that-a-ways making me a 2nd radiator!! worked great. you might think about looking in NAPA or Oreilly's books (or possibly other manufactures also).
