Only difference in 67 and newer K is
67 has the oddball idler arm mount and can be modified
Starting in 73, K's went to spool engine mounts
Here:
http://www.bigblockdart.com/techpages/techindex.shtml
The thing about pitman arms is, read the section on that page about steering boxes:
http://www.bigblockdart.com/techpages/steeringbox.shtml
You need to figure out if you box is small or large sector (this a power or manual box, I missed that)