Depends on what kinda low temps you see... it'll certainly run cool enough, too cool is the issue..
the stock one really acts more like a heater when used in conjunction with one up front...
i run just the cooler out front and have trouble getting it up to temp in the winter.. takes along time and only gets to about 160, 165.. in the summer, it heats up much quicker and gets to 180.. perfect..
but i'm strongly considering gettng my new radiator with the cooler and plumbing it in due to the long winter warmup time... thing that sucks is, it's basically gonna cost me a $100, $179 for a noncooler unit, $279 for one with.. takes 15 mins minimum for the gauge to move off 100 now in the winter when its 10, 15 degrees out.... i actually considered putting a heatlamp on the floor and run it when i wake up before i leave to heat the pan up, like a block heater... too much trouble tho..
i thought someone posted a link to some Earl's fittings for you? I hope they are available, cuz i run all steelbreaded and the Enduro fittings on that system...
isn't this what you need, inverted flare to AN?
edit*** oh, i see the prob, thats 5/8's, nothing goes down to 5/16's... they don't even have 5/16's tube to 6 an, only 3/8's tube to 6 an... hmmm, further investigation is needed... i want to know too... i hate the idea of restricting the flow down that much, but without custom rad work to run larger fittings, hmmm... maybe a call to my rad guy and see what he thinks about putting larger fittings in before i install... i'll get back to ya on what i find...