I am trying to buy 20s for my lowered '86 Silverado.  But I can’t seem to find the right wheel with correct offset with the 5 on 5 bolt pattern.  Has anybody have a similar issue.  When I test fitted one wheel the rear wheel when mount was so far back in wheel well that it looked a dually with only one wheel.  Any suggestions would be great.  I never thought that getting wheels would be so difficult.  

Well, you can get wheel spacers that will push the wheel out. Ideally, you want a wheel with the correct offset to start with, but you might have to get creative if there's a certain style of wheel you want, and it's only offered in a certain offset. With a lot of forged or multi-piece wheels, you can get custom offset and bolt patterns, but they're a lot more expensive than off-the-shelf cast wheels.