3.0 for me, too.
Both engines need a good front oil cooler, regardless, and the 3.0 is more durable as well as $2K less expensive to build, all things being equal.
I like 2.7's (have one in my own car) but wouldn't do it again, based on what I've seen lately with these engines. 2.7 "S" engines are more susceptible to case cracking now as all these things are getting pretty old and have been used hard over the years.
JMHO, given the investment required to do a proper mag-cased engine now, its foolish to spend that kind of money unless its a restoration and its imperative to retain the original engine.