this is the link that you need to solve your problems. there is a box at the bottom. click on 500 holley
http://6066gmcguy.com/performance.html
there is also a wealth of knowledge in the forum there on these engines and there has been a lot discussion on carbs(in the archives)
ron
the site changed hands a couple of years ago and a lot of the old links to the site don't work any more, but all of the info is available
http://6066gmcguy.com/