I have a nismo 62 in my GTR and it warms up to 70 fine before 5 mins.
Also have a 40mm Race Radiators alloy rad.
Have not booted it, but it holds temps at 72ish quite nicely.
Also, for completeness, I have a Serck oil cooler without a thermo and after 5-10 mins both water and oil temps dont budge from 70ish.
These are defi gauges so should be pretty accurate.