I would like to know for a fact, but don't have the time for the research & comparison.
As to the $3M, how much was he paid for his first GU contract, when was the extension and for how long, and what was the $ bump? Again, research. We would also need to compare the schools and their budgets. Or, was it JT3 pushing for his son to have that Top 8 salary?
Ask and ye shall receive:
Here is the list of coaches that made the NCAA Tournament either of the past two seasons and who were listed by USA Today as making between $2.5M and $3.5M (an admittedly somewhat random range that I am viewing as III's salary "peers"). There may well be more coaches than this that make in that range, but if they didn't make the tournament either last year or the year before, they almost surely don't meet your criteria. Next to their name is how many NCAA Tournaments they've qualified for at their current job:
Scott Drew (6/13, including this year as a make)
Travis Ford (5/8, including this year as a miss)
Rick Barnes (fired after qualifying 16 out of 17 years at Texas; won't qualify this year at Tenn and probably isn't making $3M there anyway.)
Steve Alford (2/3, including this year as a likely miss; 3/6 at previous job)
Lon Kruger (4/5, including this year as a make)
Jay Wright (11/15, including this year; 11/12 if you take away his first three years)
Bo Ryan (14/14, not counting this year one way or the other)
Tom Crean (4/8 including this year as a make; 4/5 if you takeaway his first three years)
Bobby Huggins (7/9, including this year as a make)
Thad Matta (9/11)
Sean Miller (5/7)
Josh Pastner (4/7)
III (8/12)
Your criteria was 80%. Let's be generous and list here those over 75%. It's Rick Barnes, Lon Kruger, Bo Ryan, Bobby Huggins, Thad Matta, and III. I'll also include Wright given recency, since he's way over 80% if you take away those three years.
So only seven (counting Wright) of the thirteen names have qualified 75% of the time or more. With III among them.
For each of those schools, here's the most recent year(s) going back to the start of the coach's tenure or to 2006 (III's first year) they went through an entire season unranked. I didn't go all the way back for every school:
Texas (2012 and 2013)
Oklahoma (2012 and 2013)
Wisconsin (ranked every year...even this year)
West Virginia (2012, 2013, 2014)
Ohio State (2016...not even receiving votes in most recent poll)
Villanova (2012, 2013)
Georgetown (2016...though assuredly we'll be no. 1 in the final poll after our improbable run to the championship)
So....the only program that fits your bill is Wisconsin and Bo Ryan. That's it. Out of thirteen names.
And none of the other coaches that have qualified for the NCAAT at least 75% of the time have gone further back than 2014 in terms of being ranked at some point during a given year!
If III is overpaid....then everyone (except for the retired guy) is overpaid among his "pay peers."
But the larger point, at least for me, is that "success' is more difficult than we all think it is. If getting paid among the "top 20" (or whatever it is) makes you think you should get equivalent performance, well, here's the performance of those same guys according to your own metrics. Now, I don't deny that some of these folks have had some better (and/or more recent) postseason success, but that wasn't what you asked. And in any event, many of them really haven't.
As for III's pay, it was between $400K and $500K for his first three seasons. He parlayed his success in 2006 and 2007 into a contract extension through 2013. Hard to argue with the decision to give him a raise or extension then. He certainly was in a position to demand it. Not many bigger coaching successes circa 2007 than was III.