Jon, I thought you might be interested in how I did similar. Here's
links to some old dropbox posts. Issues with the bench in use: my son
isn't fond of the bench, wants something with a better pad; the
elevation toggle is a real pinch point; The threaded pins, while hell
for stout and very secure, are slow. But it damn sure don't wiggle or
flex.
http://metalworking.com/dropbox/HoleJig.txt
http://metalworking.com/dropbox/HoleJig01.JPG
http://metalworking.com/dropbox/HoleJig02.JPG
http://metalworking.com/dropbox/HoleJig03.JPG
http://metalworking.com/dropbox/HoleJig04.JPG
http://metalworking.com/dropbox/HoleJig05.JPG
http://metalworking.com/dropbox/HoleJig06.JPG
http://metalworking.com/dropbox/HoleJig07.JPG

http://metalworking.com/dropbox/WeightBench.txt
http://metalworking.com/dropbox/WeightBench02.jpg
http://metalworking.com/dropbox/WeightBench08.jpg
http://metalworking.com/dropbox/WeightBench09.jpg
http://metalworking.com/dropbox/WeightBench12.jpg
http://metalworking.com/dropbox/WeightBench13.jpg
http://metalworking.com/dropbox/WeightBench16.jpg
http://metalworking.com/dropbox/WeightBench17.jpg

Good luck,

Pete Keillor