Snick.....A gunfighting holster rig....
http://www.warriortalk.com/showthread.php?93922-My-Snick-Holster-Gunfighting-Rig&p=1293641#post1293641
And I don't know how many used compensated pistols, but there were 30 open shooters....The match was restricted to 125 shooters....95 in the "Championship Class" and 30 in the "Open" class.....
http://www.americanhandgunner.com/1977issues/AHND77.pdf
Trick question...There is a difference between ported and compensated.....
Even your article doesn't say that they were compensated....and erroneously says that the cuts were used as a muzzle brake....They were ported, nothing more... 
From the article you posted Grumpy...

So at least one gun was compensated. It was fired by Ray Chapman according to the quote.
I'm going to say that all the opens (30) were compensated and all the champion division guns where not. Also Grumpy thank you for this article very much! I read the whole issue from that post and was particularly entertained by three things above the rest...
1. The ad for the RCBS Rock Chucker. Especially the part that calls it fast
2. The Massad Ayoob authored article just after the nationals article. I had not realized just how long he has been a recognized contributor to handgunner.
3. The ad for Vega 1911 frames on page 68. Lol I've heard about these but have never seen one. Unless the name changed and I just don't realize what I'm looking at.
Great job Grumpy!