Google something like "1987 Chevy pickup emission hose routing" and select "images" at the top of the screen. You'll get a ton of stuff you don't want, but you may find the correct one.
My 1982 C10's sticker for the orginal 250 six cyl engine looks like this:
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Hey, I just found this one for 87 Chevy truck, but don't know which engine:
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